Resin and photoresist composition comprising the same

ABSTRACT

The present invention provides a resin comprising a structural unit represented by the formula (aa): 
     
       
         
         
             
             
         
       
     
     wherein T 1  represents a C4-C34 sultone ring group optionally having one or more substituents, X 2  represents —O— or —N(R c )—, R c  represents a hydrogen atom or a C1-C6 alkyl group, when X 2  is —O—, Z 1  represents *—X 1 —, *—X 3 —CO—O—X 1 —, *—X 3 —CO—N(R c )—X 1 —, *—X 3 —O—CO—X 1 — or *—X 3 —N(R c )—CO—X 1 —, when X 2  is —N(R c )—, Z 1  represents *—X 1 —, *—X 1 —O—X 3 —, *—X 1 —CO—, *—X 1 —X 4 —CO—X 3 —, *—X 1 —CO—X 4 —X 3 —, *—X 1 —X 4 —CO—X 3 —CO— or *—X 1 —CO—X 4 —X 3 —CO—, X 1  and X 3  independently each represent a C1-C6 divalent aliphatic hydrocarbon group, X 4  represents —O— or —N(R c )—, * represents a binding position to X 2 , and R 1  represents a C1-C6 alkyl group optionally having one or more halogen atoms, a hydrogen atom or a halogen atom.

This nonprovisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2010-250556 filed in JAPAN on Nov. 9, 2010 andon patent Application No. 2010-250556 filed in JAPAN on Nov. 9, 2010,the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a resin and a photoresist compositioncomprising the same.

BACKGROUND OF THE INVENTION

A photoresist composition is used for semiconductor microfabricationemploying a lithography process. The photoresist composition comprisesan acid generator and a resin having an acid-labile group, beinginsoluble or poorly soluble in an aqueous alkali solution but becomingsoluble in an aqueous alkali solution by the action of an acid.

US 2009/0068590 A1 discloses a resin consisting of the followingstructural units.

US 2010/0086873 A1 discloses a resin consisting of the followingstructural units.

SUMMARY OF THE INVENTION

The present invention is to provide a resin and a photoresistcomposition comprising the same.

The present invention relates to the followings:

[1] A resin comprising a structural unit represented by the formula(aa):

wherein T¹ represents a C4-C34 sultone ring group optionally having oneor more substituents, X² represents —O— or —N(R^(c))—, R^(c) representsa hydrogen atom or a C1-C6 alkyl group, when X² is —O—, Z¹ represents*—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹, when X² is —N(R^(c))—, Z¹ represents *—X¹—,*—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³—, *—X¹—CO—X⁴—X³—, *—X¹—X⁴—CO—X³—CO—or *—X¹—CO—X⁴—X³—CO—, X¹ and X³ independently each represent a C1-C6divalent aliphatic hydrocarbon group, X⁴ represents —O— or —N(R^(c))—, *represents a binding position to X², and R¹ represents a C1-C6 alkylgroup optionally having one or more halogen atoms, a hydrogen atom or ahalogen atom;[2] The resin according to [1], wherein X² is —O— or —N(R^(c))— and Z¹is *—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹— in the formula (aa);[3] The resin according to [1], wherein X² is —NH—, and Z¹ represents—X¹—, *—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³—, *—X¹—X⁴—CO—X³—CO— or*—X¹—CO—X⁴—X³—CO— in the formula (aa);[4] The resin according to any one of [1] to [3], wherein the C1-C6divalent aliphatic hydrocarbon group is a C1-C6 alkanediyl group;[5] The resin according to any one of [1] to [4], wherein T¹ is apolycyclic sultone ring group in the formula (aa);[6] The resin according to any one of [1] to [4], wherein T¹ is a grouprepresented by the formula (T1):

wherein X¹¹, H¹² and X¹³ independently each represent —O—, —S— or —CH₂—,one or two hydrogen atoms in —CH₂— in the formula (T1) may be replacedby a halogen atom, a hydroxyl group, a cyano group, a C1-C12 alkyl groupoptionally having a halogen atom or a hydroxyl group, a C1-C12 alkoxygroup, a C6-C12 aryl group, a C7-C12 aralkyl group, a glycidyloxy group,a C2-C12 alkoxycarbonyl group or a C2-C4 acyl group, and * represents abinding position to —O—, in the formula (aa);[7] The resin according to any one of [1] to [6], wherein —X²—Z¹— is—O—CH₂—CH₂—, —O—CH₂—CH₂—O—CO—CH₂— or —O—CH₂—CH₂—NH—CO—CH₂— in theformula (aa);[8] The resin according to any one of [1] to [6], wherein —X²—Z¹— is—NH—CH₂—O— in the formula (aa);[9] The resin according to any one of [1] to [8], wherein the resin isone being insoluble or poorly soluble in an aqueous alkali solution butbecoming soluble in an aqueous alkali solution by the action of an acid;[10] A photoresist composition comprising the resin according to [9] andan acid generator;[11] The photoresist composition according to [10], which furthercomprises a solvent;[12] The photoresist composition according to [10], which furthercomprises a basic compound;[13] The photoresist composition according to [11], which furthercomprises a basic compound;[14] A process for producing a photoresist pattern comprising:

(1) a step of applying the photoresist composition according to [10],[11], [12] or [13] on a substrate to form a photoresist compositionlayer,

(2) a step of forming a photoresist film by drying the photoresistcomposition layer formed,

(3) a step of exposing the photoresist film to radiation,

(4) a step of heating the photoresist film after exposing, and

(5) a step of developing the photoresist film after heating;

[15] A compound represented by the formula (aa′):

wherein T¹ represents a C4-C34 sultone ring group optionally having oneor more substituents, X² represents —O— or —N(R^(c))—, R^(c) representsa hydrogen atom or a C1-C6 alkyl group, when X² is —O—, Z¹ represents*—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹—, when X² is —N(R^(c)) Z¹ represents *—X¹—,*—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³, *—X¹—CO—X⁴—X³—, *—X¹—X⁴—CO—X³—CO—or *—X¹—CO—X⁴—X³—CO—, X¹ and X³ independently each represent a C1-C6divalent aliphatic hydrocarbon group, X⁴ represents —O— or —N(R^(c))—, *represents a binding position to X², and R¹ represents a C1-C6 alkylgroup optionally having one or more halogen atoms, a hydrogen atom or ahalogen atom.

DESCRIPTION OF PREFERRED EMBODIMENTS

The resin of the present invention (hereinafter, simply referred to asRESIN (A)) comprises a structural unit represented by the formula (aa):

wherein T¹ represents a C4-C34 sultone ring group optionally having oneor more substituents, X² represents —O— or —N(R^(c))—, R^(c) representsa hydrogen atom or a C1-C6 alkyl group, when X² is —O—, Z¹ represents *—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹—, when X² is —N(R^(c)) Z¹ represents *—X¹—,*—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³, *—X¹—CO—X⁴—X³, *—X¹—X⁴—CO—X³—CO— or*—X¹—CO—X⁴—X³—CO—, X¹ and X³ independently each represent a C1-C6divalent aliphatic hydrocarbon group, X⁴ represents —O— or —N(R^(c))—, *represents a binding position to X², and R¹ represents a C1-C6 alkylgroup optionally having one or more halogen atoms, a hydrogen atom or ahalogen atom.

In this specification, “sultone ring group” means a cyclic group having—O—SO₂— within a ring structure. The cyclic group can further containone or more heteroatoms such as an oxygen atom, a sulfur atom and anitrogen atom, and as the heteroatom, an oxygen atom is preferable.

Examples of the sultone ring group include the group represented by thefollowing formula (T¹-1), (T¹-2), (T¹-3) or (T¹-4), and in the followingformulae, * represents a binding position to —O—.

The sultone ring group may have one or more substituents, and examplesthereof include a halogen atom, a hydroxyl group, a cyano group, aC1-C12 alkyl group optionally having a halogen atom or a hydroxyl group,a C1-C12 alkoxy group, a C6-C12 aryl group, a C7-C12 aralkyl group, aglycidyloxy group, a C2-C12 alkoxycarbonyl group and a C2-C4 acyl group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the C1-C12 alkyl group include a linear or branched chainalkyl group such as a methyl group, an ethyl group, a propyl group, anisopropyl group, a butyl group, an isobutyl group, a tert-butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a decylgroup and a dodecyl group, and a C1-C6 alkyl group is preferable and amethyl group is more preferable.

Examples of the C1-C12 alkyl group having a halogen atom or a hydroxylgroup include a hydroxymethyl group, a hydroxyethyl group and atrifluoromethyl group.

Examples of the C1-C12 alkoxy group include a linear or branched chainalkoxy group such as a methoxy group, an ethoxy group, a propoxy group,an isopropoxy group, a butoxy group, an isobutoxy group, a tert-butoxygroup, a pentyloxy group, a hexyloxy group, a heptyloxy group, anoctyloxy group, a decyloxy group and a dodecyoxy group.

Examples of the C6-C12 aryl group include a phenyl group, a naphthylgroup, an anthryl group and a biphenyl group.

Examples of the C7-C12 aralkyl group include a benzyl group, aphenylethyl group, a phenylpropyl group, a naphthylmethyl group and anaphthylethyl group.

The C2-C12 alkoxycarbonyl group is a group formed by bonding a C1-C11alkoxy group with a carbonyl group, and examples thereof include amethoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group,an isopropoxycarbonyl group, a butoxycarbonyl group, anisobutoxycarbonyl group, a tert-butoxycarbonyl group, apentyloxycarbonyl group, a hexyloxycarbonyl group, a heptyloxycarbonylgroup, an octyloxycarbonyl group and a decyloxycarbonyl group, and aC2-C6 alkoxycarbonyl group is preferable and a methoxycarbonyl group ismore preferable.

Examples of the C2-C4 acyl group include an acetyl group, a propionylgroup and a butyryl group.

From the viewpoint of easy production of a monomer giving the structuralunit represented by the formula (aa), an unsubstituted sultone ringgroup is preferable.

The sultone ring group may be a monocyclic sultone ring group or apolycyclic sultone ring group, and the polycyclic sultone ring group ispreferable.

It is preferred that T¹ is a group represented by the formula (T1):

wherein X¹¹, X¹² and X¹³ independently each represent —O—, —S— or —CH₂—,one or two hydrogen atoms in —CH₂— in the formula (T1) may be replacedby a halogen atom, a hydroxyl group, a cyano group, a C1-C12 alkyl groupoptionally having a halogen atom or a hydroxyl group, a C1-C12 alkoxygroup, a C6-C12 aryl group, a C7-C12 aralkyl croup, a glycidyloxy group,a C2-C12 alkoxycarbonyl group or a C2-C4 acyl group, and * represents abinding position to —O—, in the formula (aa), and it is more preferredthat T¹ is an unsubstituted group represented by the formula (T1).

It is preferred that X¹¹, X¹² and X¹³ independently each represent —O—or —CH₂—, and it is more preferred that X¹¹, X¹² and X¹³ are —CH₂—. Whenone of X¹¹, X¹² and X¹³ is —O—, it is preferred that the other two are—CH₂—. When one of X¹¹, X¹² and X¹³ is —O—, it is preferred that X¹¹ is—O—.

Preferable examples of T¹ include the following groups, and in thefollowing formulae, * represents a binding position to —O—.

In the formula (aa), X² represents —O— or —N(R^(c))—, R^(c) represents ahydrogen atom or a C1-C6 alkyl group, when X² is —O—, Z¹ represents—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹—, when X² is —N(R^(c))—, Z¹ represents *—X¹—,*—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³—, *—X¹—CO—X⁴—X³—, *—X¹—X⁴—CO—X³—CO—or *—X¹—CO—X⁴—X³—CO—, X¹ and X³ independently each represent a C1-C6divalent aliphatic hydrocarbon group, X⁴ represents —O— or —N(R^(c))—, *represents a binding position to X².

Hereinafter, “divalent aliphatic hydrocarbon group” includes a divalentchain aliphatic hydrocarbon group, a divalent alicyclic hydrocarbongroup and a divalent group formed by combining a chain aliphatichydrocarbon group with an alicyclic hydrocarbon group.

As the C1-C6 divalent aliphatic hydrocarbon group, a C1-C6 alkanediylgroup is preferable and a C1-C4 alkanediyl group is more preferable.

Examples of the C1-C6 alkanediyl group include a linear or branchedchain alkanediyl group such as a methylene group, an ethane-1,1-diylgroup, an ethane-1,2-diyl group, a propane-1,1-diyl group, apropane-2,2-diyl group, a propane-1,3-diyl group, a propane-1,2-diylgroup, a butane-1,3-diyl group, a butane-1,4-diyl group, apentane-1,5-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group. A linear chain alkanediyl group ispreferable.

At least one of X¹ and X³ is preferably a C1-C6 alkanediyl group, andboth thereof are more preferably C1-C6 alkanediyl groups.

When X² is —O—, X³ is preferably a C1-C3 alkanediyl group, morepreferably a methylen group or an ethylene group. When X² is —O—, X¹ ispreferably a C1-C4 alkanediyl group, more preferably a methylen group oran ethylene group, and especially preferably a methylene group.

In the formula (aa), —X²—Z¹— is preferably —O—CH₂—CH₂—,—O—CH₂—CH₂—O—CO—CH₂— or —O—CH₂—CH₂—NH—CO—CH₂—.

When X² is —N(R^(c))—, R^(1c) is preferably a hydrogen atom. X⁴ ispreferably —O— or —NH—, and more preferably —O—.

When X² is —N(R^(c))— and Z¹ is *—X¹—, X¹ is preferably a C1-C4alkanediyl group, more preferably a methylene group or ethylene group,and especially preferably a methylene group.

When X² is —N(R^(c))— and Z¹ is *—X¹—O—X³—, a total carbon number of X¹and X³ is preferably 2 to 4, and more preferably 3. Preferable examplesof *—X¹—O—X³— include *—CH₂—O—CH₂—, *—CH₂—CH₂—O—CH₂—,*—CH₂—CH₂—CH₂—O—CH₂— and *—CH₂—CH₂—O—CH₂—CH₂—, and *—CH₂—CH₂—O—CH₂— ismore preferable.

When X² is —N(R^(c))— and Z¹ is *—X¹—CO—, a carbon number of X¹ ispreferably 1 to 4, and more preferably 1 to 3. Preferable examples of*—X¹—CO— include *—CH₂—CO—, *—CH₂—CH₂—CO— and *—CH₂—CH₂—CH₂—CO—, and*—CH₂—CO— is more preferable.

When X² is —N(R^(c))— and Z¹ is *—X¹—X⁴—CO—X³—, a total carbon number ofX¹ and X³ is preferably 2 to 4, and more preferably 3. X⁴ is preferably—O— or —NH—, and more preferably —O—. Preferable examples of*—X¹—X⁴—CO—X³— include *—CH₂—O—CO—CH₂—, *—CH₂—CH₂—O—CO—CH₂—,*—CH₂—CH₂—CH₂—O—CO—CH₂—, *—CH₂—NH—CO—CH₂—, *—CH₂—CH₂—NH—CO—CH₂— and*—CH₂—CH₂—CH₂—NH—CO—CH₂—, and *—CH₂—CH₂—O—CO—CH₂— is more preferable.

When X² is —N(R^(c))— and Z¹ is *—X¹—CO—X⁴—X³—, a total carbon number ofX¹ and X³ is preferably 2 to 4, and more preferably 3. X⁴ is preferably—O— or —NH—, and more preferably —O—. Preferable examples of*—X¹—CO—X²—X³— include *—CH₂—CO—O—CH₂—, *—CH₂—CH₂—CO—O—CH₂—,*—CH₂—CH₂—CH₂—CO—O—CH₂—, *—CH₂—CO—O—CH₂—CH₂—, *—CH₂—CO—NH—CH₂—,*—CH₂—CH₂—CO—NH—CH₂—, *—CH₂—CH₂—CH₂—CO—NH—CH₂— and *—CH₂—CO—NH—CH₂—CH₂—,and *—CH₂—CO—O—CH₂—CH₂— is more preferable.

When X² is —N(R^(c))— and Z¹ is *—X¹—X⁴—CO—X³—CO—, a total carbon numberof X¹ and X³ is preferably 2 to 4, and more preferably 3. X⁴ ispreferably —O— or —NH—, and more preferably —O—. Preferable examples of*—X¹—X⁴—CO—X³—CO— include *—CH₂—O—CO—CH₂—CO—, *—CH₂—CH₂—O—CO—CH₂—CO—,*—CH₂—CH₂—CH₂—O—CO—CH₂—CO—, —CH₂—NH—CO—CH₂—CO—, *—CH₂—CH₂—NH—CO—CH₂—CO—and *—CH₂—CH₂—CH₂—NH—CO—CH₂—CO—, and *—CH₂—CH₂—O—CO—CH₂—CO— is morepreferable.

When X² is —N(R^(c))— and Z¹ is *—X¹—CO—X⁴—X³—CO—, a total carbon numberof X¹ and X³ is preferably 2 to 4, and more preferably 3. X⁴ ispreferably —O— or —NH—, and more preferably —O—. Preferable examples of*—X¹—CO—X⁴—X³—CO— include , *—CH₂—CO—O—CH₂—CO—, *—CH₂—CH₂—CO—O—CH₂—CO—,*—CH₂—CH₂—CH₂—CO—O—CH₂—CO—, *—CH₂—CO—O—CH₂—CH₂—CO—, *—CH₂—CO—NH—CH₂—CO—,*—CH₂—CH₂—CO—NH—CH₂—CO—, *—CH₂—CH₂—CH₂—CO—NH—CH₂—CO— and*—CH₂—CO—NH—CH₂—CH₂—CO—, and *—CH₂—CO—O—CH₂—CH₂—CO— is more preferable.

When X² is —N(R^(c))— and Z¹ preferably contains —CO—, and it is morepreferably *—X¹—CO— and especially preferably *—CH₂—CO—.

R¹ is preferably an unsubstituted alkyl group or a hydrogen atom, morepreferably a C1-C3 alkyl group or a hydrogen atom, and especiallypreferably a methyl group or a hydrogen atom.

Examples of the structural unit represented by the formula (aa) includethe structural units represented by the formulae (aa-1) to (aa-56).

Examples of the structural unit represented by the formula (aa) includethe structural units represented by the formulae (aa-1) to (aa-24)wherein the flowing partial structure M is replaced by the followingpartial structure A1, A2 or A3.

Examples of the structural unit represented by the formula (aa) includethe structural units represented by the formulae (aa-25) to (aa-56)wherein the above-mentioned partial structure A2 is replaced by theabove-mentioned partial structure A3.

The structural unit represented by the formula (aa) is derived from acompound represented by the formula (aa′):

wherein T¹, Z¹, X² and R¹ are the same as defined above (hereinafter,simply referred to as the compound (aa′)).

The compound (aa′) can be produced by the following. For example, thecompound (aa) wherein X² is —O— and Z¹ is —CH₂—CH₂— can be produced byreacting a compound represented by the formula (aa1-a) with a compoundrepresented by the formula (aa1-b) in a solvent such as acetonitrile inthe presence of a catalyst.

In the above-mentioned formula, X represents a halogen atom, andexamples thereof include a chlorine atom, a bromine atom and an iodineatom, and an iodine atom is preferable. Examples of the catalyst includepotassium carbonate and potassium iodide.

The compound represented by the formula (aa1-a) can be producedaccording to known methods. For example, the compound represented by theformula (aa1-a) can be produced by reacting a compound represented bythe formula (aa1-c) with a compound represented by the formula (aa1-d)in a solvent such as tetrahydrofuran in the presence of a basic catalystsuch as pyridine.

In the above-mentioned formula, X′ represents a halogen atom, andexamples thereof include a chlorine atom, a bromine atom and an iodineatom, and an iodine atom is preferable.

Examples of the compound represented by the formula (aa1-c) includemethacrylic chloride which is commercially available.

Examples of the compound represented by the formula (aa1-d) include2-haloethanol which is commercially available. Among them, preferred is2-iodoethanol.

Examples of the compound represented by the formula (aa1-b) includecompounds formed by bonding —OH to of the groups represented by theabove-mentioned formulae (T¹-1) to (T¹-4). Examples of the compoundrepresented by the formula (aa1-b) include the following, and thiscompound is commercially available.

The compound (aa′) wherein X² is —NH— can be produced by the same asdescribed above except that a compound represented by the formula(aa1-a1) is used in place of the compound represented by the formula(aa1-a).

wherein R¹ is the same as defined above.

The compound (aa′) wherein X² is —NH— can be also produced by the sameas described above except that a 2-haloethylamine is used in place ofthe 2-haloethanol. The amino group of the 2-haloethylamine may beprotected.

The compound (aa′) wherein X² is —O— and Z¹ is —CH₂—CH₂—O—CO—CH₂— can beproduced by reacting a compound represented by the formula (aa2-a) witha compound represented by the formula (aa2-b) in a solvent such asacetonitrile.

Examples of the compound represented by the formula (aa2-a) include2-hydroxyethyl methacrylate.

The compound represented by the formula (aa2-b) can be produced byreacting a compound represented by the formula (aa2-c) with a compoundrepresented by the formula (aa2-d) in a solvent such as tetrahydrofuran.

The compound represented by the formula (aa2-d) can be produced byreacting a compound represented by the formula (aa2-e) with a compoundrepresented by the formula (aa2-f) in a solvent such as chloroform.

Examples of the compound represented by the formula (aa2-e) include thefollowing.

The compound (aa′) wherein X² is —NH— and Z¹ is —CH₂—CO— can be producedby reacting a compound represented by the formula (aa1-b) with acompound represented by the formula (aa3-a) in a solvent such astetrahydrofuran and acetonitrile.

The compound represented by the formula (aa3-a) can be produced byreacting a compound represented by the formula (aa3-c) with a compoundrepresented by the formula (aa3-d) in a solvent such as dichloromethane.

Examples of the compound represented by the formula (aa3-c) include thefollowing.

Examples of the compound represented by the formula (aa′) include thefollowing.

The content of the structural unit represented by the formula (aa) inRESIN (A) is preferably 2 to 40% by mole, more preferably 3 to 35% bymole and especially preferably 5 to 30% by mole based on 100% by mole ofall the structural units of RESIN (A).

RESIN (A) is preferably a resin having an acid-labile group and beinginsoluble or poorly soluble in an aqueous alkali solution, and the resinis one capable of being soluble in an aqueous alkali solution by theaction of an acid.

In the photoresist composition of the present invention, an acid isgenerated from the acid generator contained therein by exposure. Theacid catalytically acts against the acid-labile group in the resin tocleave the acid-labile group, and the resin becomes one being soluble inan aqueous alkali solution.

When RESIN (A) is a resin becoming soluble in an aqueous alkali solutionby the action of an acid, the resin can be produced by polymerizing thecompound (aa′) with a monomer having an acid-labile group. Two kinds ofthe monomer having an acid-labile group can be used in combination. Inthis specification, “an acid-labile group” means a group capable ofbeing eliminated by the action of an acid.

Examples of the acid-labile group include a group represented by theformula (1):

wherein R^(a1), R^(a2) and R^(a3) independently each represent a C1-C8aliphatic hydrocarbon group, and R^(a1) and R^(a2) can be bonded eachother to form a C3-C20 ring together with a carbon atom to which R^(a1)and R^(a2) are bonded, and one or more —CH₂— in the aliphatichydrocarbon group and the ring can be replaced by —O—, —S— or —CO—.

The group represented by the formula (1) has a structure wherein atertiary carbon atom is bonded to —O—.

“Aliphatic hydrocarbon group” represented by R^(a1), R^(a2) and R^(a3)contains a chain aliphatic hydrocarbon group, an alicyclic hydrocarbongroup and a group formed by combining a chain aliphatic hydrocarbongroup with an alicyclic hydrocarbon group.

Examples of the C1-C8 aliphatic hydrocarbon group include a C1-C8 alkylgroup and a C3-C8 alicyclic hydrocarbon group. Examples of the C1-C8alkyl group include a methyl group, an ethyl group, a propyl group, anisopropyl group, a butyl group, a pentyl group, a 1-methylpentyl group,a hexyl group, a 1,4-dimethylhexyl group, a heptyl group, a1-methylheptyl group and an octyl group. The C3-C8 alicyclic hydrocarbongroup may be monocyclic or polycyclic. Examples of the C3-C8 alicyclichydrocarbon group include groups formed by removing a hydrogen atom fromthe following cycloalkanes.

When R^(a1) and R^(a2) are bonded each other, they form a C3-C20 ringtogether with a carbon atom to which they are bonded, examples of thering include an aliphatic ring and an aromatic ring, and a C3-C12 ringis preferable. When R^(a1) and R^(a2) are bonded each other to form aring together with a carbon atom to which R^(a1) and R^(a2) are bonded,examples of the group represented by —C(R^(a1))(R^(a2))(R^(a3)) includethe following groups.

wherein R^(a3) is the same as defined above.

Examples of the acid-labile group include a group represented by theformula (1) wherein R^(a1), R^(a2) and R^(a3) independently eachrepresent an alkyl group such as a tert-butyl group, a group representedby the formula (1) wherein R^(a1) and R^(a2) are bonded each other toform an adamantyl ring and R^(a3) is an alkyl group such as a2-alkyl-2-adamantyl group, and a group represented by the formula (1)wherein R^(a1) and R^(a2) are alkyl groups and R^(a3) is an adamantylgroup such as a 1-(1-adamantyl)-1-alkylalkoxycarbonyl group.

Examples of the acid-labile group include a group represented by theformula (2):

wherein R^(b1) and R^(b2) independently each represent a hydrogen atomor a C1-C20 hydrocarbon group, and R^(b3) represents a C1-C20hydrocarbon group, and R^(b2) and R^(b3) can be bonded each other toform a C3-C20 ring together with the carbon atom and the oxygen atom towhich they are bonded, and one or more —CH₂— in the hydrocarbon groupand the ring can be replaced by —O— or —S—, and * represents a bindingposition.

The group represented by the formula (2) has an acetal structure.

Examples of the hydrocarbon group include an aliphatic hydrocarbon groupand an aromatic hydrocarbon group.

“Aliphatic hydrocarbon group” represented by R^(a1), R^(a2) and R^(a3)contains a chain aliphatic hydrocarbon group, an alicyclic hydrocarbongroup and a group formed by combining a chain aliphatic hydrocarbongroup with an alicyclic hydrocarbon group.

Examples of the chain aliphatic hydrocarbon group include a C1-C20linear or branched chain alkyl group such as a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group, a decyl group, adodecyl group, a hexadecyl group, a pentadecyl group, a hexadecyl group,a heptadecyl group and an octadecyl group, and groups formed by removinga hydrogen atom from the following cycloalkanes.

Examples of the aromatic hydrocarbon group include an aryl group such asa phenyl group, a naphthyl group, an anthryl group, a biphenyl group, aphenanthryl group and a fluorenyl group.

It is preferred that at least one of R^(b1) and R^(b2) is a hydrogenatom.

Examples of the group represented by the formula (2) include thefollowing.

The monomer having an acid-labile group is preferably a monomer havingan acid-labile group in its side chain and a carbon-carbon double bond,and is more preferably an acrylate monomer having an acid-labile groupin its side chain or a methacryalte monomer having an acid-labile groupin its side chain. An acrylate monomer having the group represented bythe formula (1) or (2) in its side chain or a methacryalte monomerhaving the group represented by the formula (1) or (2) in its side chainis especially preferable.

An acrylate monomer having the group represented by the formula (1) inits side chain or a methacryalte monomer having the group represented bythe formula (1) in its side chain is preferable, and an acrylate monomerhaving the group represented by the formula (1) in which R^(a1) andR^(a2) are bonded each other to form a C5-C20 saturated alicycletogether with the carbon atom to which they are bonded in its side chainor a methacryalte monomer having the group represented by the formula(1) in which R^(a1) and R^(a2) are bonded each other to form a C5-C20saturated alicycle together with the carbon atom to which they arebonded in its side chain is more preferable. When the photoresistcomposition contains a resin derived from a monomer having a bulkystructure such as a saturated alicyclic hydrocarbon group, thephotoresist composition having excellent resolution tends to beobtained.

Preferable examples of the structural unit derived from the monomerhaving an acid-labile group include the structural units represented bythe formulae (a1-1) and (a1-2):

wherein R^(a4) and R^(a5) each independently represents a hydrogen atomor a methyl group, R^(a6) and R^(a7) each independently represents aC1-C10 aliphatic hydrocarbon group, L^(a1) and L^(a2) each independentlyrepresents *—O— or *—O—(CH₂)_(k1)—CO—O— in which * represents a bindingposition to —CO—, and k1 represents an integer of 1 to 7, and m1represents an integer of 0 to 14, n1 represents an integer of 0 to 10,and n2 represents 0 or 5.

L^(a1) is preferably *—O— or *—O—(CH₂)_(f1)—CO—O— in which * representsa binding position to —CO—, and f1 represents an integer of 1 to 4, andis more preferably *—O— or *—O—CH₂—CO—O—, and is especially preferably*—O—. L^(a2) is preferably *—O— or *—O— (CH₂)_(f1)—CO—O— in which *represents a binding position to —CO—, and f1 is the same as definedabove, and is more preferably *—O— or *—O—CH₂—CO—O—, and is especiallypreferably *—O—.

R^(a4) and R^(a5) are preferably methyl groups.

The aliphatic hydrocarbon group represented by R^(a6) and R^(a7) ispreferably C1-C8 alkyl group or C3-C10 alicyclic hydrocarbon group. Itis preferred that R^(a6) and R^(a7) independently each represent C1-C8alkyl group or C3-C8 alicyclic hydrocarbon group, and it is morepreferred that R^(a6) and R^(a7) independently each represent C1-C6alkyl group or C3-C6 alicyclic hydrocarbon group. Examples of thealiphatic hydrocarbon group include a methyl group, an ethyl group, apropyl group, an isopropyl group, a tart-butyl group, a2,2-dimethylethyl group, a propyl group, a 1-methylpropyl group, a2,2-dimethylpropyl group, a 1-ethylpropyl group, a butyl group, a1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a1-propylbutyl group, a pentyl group, a 1-methylpentyl group, a hexylgroup, a 1,4-dimethylhexyl group, a heptyl group, a 1-methylheptyl groupand an octyl group. Examples of the alicyclic hydrocarbon group includea cyloheptyl group, a methylcyloheptyl group, a cyclohexyl group, amethylcyclohexyl group, a dimethylcyclohexyl group, a norbornyl groupand a methylnorbornyl group.

In the formula (a1-1), m1 is preferably an integer of 0 to 3, and ismore preferably 0 or 1. In the formula (a1-2), n1 is preferably aninteger of 0 to 3, and is more preferably 0 or 1, and n2 is preferably0, 1 or 2, and more preferably 0 or 1. It is preferred that k1 is aninteger of 1 to 4, and it is more preferred that k1 is 1.

Examples of the structural unit represented by the formula (a1-1)include the structural units represented by the formulae (a1-1-1) to(a1-1-38)

Examples of the structural unit represented by the formula (a1-1)include the structural units represented by the formulae (a1-1-1) to(a1-1-38) wherein the above-mentioned partial structure M is replaced bythe above-mentioned partial structure A1.

Among them, preferred are the structural units represented by theformulae (a1-1-1), (a1-1-2) and (a1-1-3) and these structures whereinthe above-mentioned partial structure M is replaced by theabove-mentioned partial structure A1, and more preferred are thestructural units represented by the formulae (a1-1-1), (a1-1-2) and(a1-1-3), and especially preferred are the structural units representedby the formulae (a1-1-1) and (a1-1-2). These preferable structural unitscan be derived from 2-methyl-2-adamantyl acrylate, 2-methyl-2-adamantylmethacrylate, 2-ethyl-2-adamantyl acrylate, 2-ethyl-2-adamantylmethacrylate, 2-isopropyl-2-adamantyl acrylate and2-isopropyl-2-adamantyl methacrylate.

Examples of the structural unit represented by the formula (a1-2)include the structural units represented by the formulae (a1-2-1) to(a1-2-12).

Examples of the structural unit represented by the formula (a1-2)include the structural units represented by the formulae (a1-2-1) to(a1-2-12) wherein the above-mentioned partial structure M is replaced bythe above-mentioned partial structure A1.

Among them, preferred are the structural units represented by theformulae (a1-2-1), (a1-2-2), (a1-2-4) and (a1-2-5) and these structureswherein the above-mentioned partial structure M is replaced by theabove-mentioned partial structure A1, and more preferred are thestructural units represented by the formulae (a1-2-4) and (a1-2-5) andthese structures wherein the above-mentioned partial structure M isreplaced by the above-mentioned partial structure A1. These preferablestructural units can be derived from 1-ethyl-1-cyclohexyl acrylate,1-ethyl-1-cyclohexyl methacrylate, and the like.

The content of the structural unit represented by the formula (a1-1) or(a1-2) in RESIN (A) is usually 10 to 95% by mole, preferably 15 to 90%by mole and more preferably 20 to 85% by mole and especially preferably25 to 60% by mole based on 100% by mole of all the structural units ofRESIN (A).

The content of the structural unit represented by the formula (a1-1) or(a1-2) in RESIN (A) can be adjusted by adjusting the amount of themonomer giving the structural unit represented by the formula (a1-1) or(a1-2) based on the total amount of the monomers used for producingRESIN (A). Specifically, the amount of the monomer giving the structuralunit represented by the formula (a1-1) or (a1-2) is usually 10 to 95% bymole, preferably 15 to 90% by mole and more preferably 20 to 85% by moleand especially preferably 25 to 60% by mole based on 100% by mole of allthe monomers used for producing RESIN (A).

Other examples of the monomer having an acid-labile group include amonomer represented by the formula (a1-3):

wherein R^(a9) represents a hydrogen atom, a C1-C3 alkyl group which canhave one or more hydroxyl groups (—OH), a carboxyl group (—COOH), acyano group or a —COOR^(a13) group in which R^(a13) represents a C1-C20aliphatic hydrocarbon group, and the aliphatic hydrocarbon group canhave one or more hydroxyl groups, and one or more —CH₂— in the aliphatichydrocarbon group can be replaced by —O— or —CO—, R^(a10), R^(a11) andR^(a12) each independently represent a C1-C20 aliphatic hydrocarbongroup, and R^(a10) and R^(a11) can be bonded each other to form a C3-C20ring together with the carbon atom to which R^(a10) and R^(a11) arebonded, and the aliphatic hydrocarbon group can have one or morehydroxyl groups, and one or more —CH₂— in the aliphatic hydrocarbongroup can be replaced by —O— or —CO—.

When RESIN (A) has a structural unit derived from the monomerrepresented by the formula (a1-3), the photoresist composition havingexcellent resolution and higher dry-etching resistance tends to beobtained.

Examples of the C1-C3 alkyl group which can have one or more hydroxylgroups include a methyl group, an ethyl group, a propyl group, ahydroxymethyl group and a 2-hydroxyethyl group. Examples of thealiphatic hydrocarbon group represented by R^(a10), R^(a11) and R^(a12)include a chain hydrocarbon group such as an alkyl group and analicyclic hydrocarbon group and examples thereof include the same asdescribed above. Examples of R^(a10), R^(a11) and R^(a12) include amethyl group, an ethyl group, a cyclohexyl group, a methylcyclohexylgroup, a hydroxycyclohexyl group, an oxocyclohexyl group and anadamantyl group.

Examples of the ring formed by bonding R^(a10) and R^(a11) each othertogether with the carbon atom to which R^(a10) and R^(a11) are bondedinclude a cyclohexane ring and an adamantine ring.

Examples of R^(a13) include a methyl group, an ethyl group, a propylgroup, a 2-oxo-oxolan-3-yl group and a 2-oxo-oxolan-4-yl group.

Examples of the monomer represented by the formula (a1-3) includetert-butyl 5-norbornene-2-carboxylate, 1-cyclohexyl-1-methylethyl5-norbornene-2-carboxylate, 1-methylcyclohexyl5-norbornene-2-carboxylate, 2-methyl-2-adamantyl5-norbornene-2-carboxylate, 2-ethyl-2-adamantyl5-norbornene-2-carboxylate, 1-(4-methylcyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-(4-hydroxylcyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-methyl-1-(4-oxocyclohexyl)ethyl5-norbornene-2-carboxylate and 1-(1-adamantyl)-1-methylethyl5-norbornene-2-carboxylate.

When RESIN (A) contains the structural unit derived form the monomerrepresented by the formula (a1-3), the content of the structural unitderived from the monomer represented by the formula (a1-3) is usually 10to 95% by mole and preferably 15 to 90% by mole and more preferably 20to 85% by mole based on total molar of all the structural units of RESIN(A).

Other examples of the compound having an acid-labile group include amonomer represented by the formula (a1-4):

Wherein R^(a32) represents a hydrogen atom, a halogen atom, a C1-C6alkyl group or a C1-C6 halogenated alkyl group, R^(a33) is independentlyin each occurrence a halogen atom, a hydroxyl group, a C1-C6 alkylgroup, a C1-C6 alkoxy group, a C2-C4 acyl group, a C2-C4 acyloxy group,an acryloyl group or a methacryloyl group, 1a represents an integer of 0to 4, R^(a34) and R^(a35) each independently represent a hydrogen atomor a C1-C12 hydrocarbon group, X^(a2) represents a single bond or aC1-C17 divalent saturated hydrocarbon group in which one or more —CH₂—can be replaced by —O—, —CO—, —S—, —SO₂— or —N(R^(c))— wherein R^(c)represents a hydrogen atom or a C1-C6 alkyl group, and Y^(a3) representsa C1-C18 hydrocarbon group, and the C1-C17 divalent saturatedhydrocarbon group and the C1-C18 hydrocarbon group can have one or moresubstituents selected from the group consisting of a halogen atom, ahydroxyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C4 acylgroup and a C2-C4 acyloxy group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the C1-C6 alkyl group include the same as described above,and a C1-C4 alkyl group is preferable and a C1-C2 alkyl group is morepreferable and a methyl group is especially preferable.

Examples of the C1-C6 halogenated alkyl group include a trifluoromethylgroup, a pentafluoroethyl group, a heptafluoropropyl group, aheptafluoroisopropyl group, a nonafluorobutyl group, anonafluoro-sec-butyl group, a nonafluoro-tert-butyl group, aperfluoropentyl group, a perfluorohexyl group, a perchloromethyl group,a perbromomethyl group and a periodomethyl group.

Examples of the C1-C6 alkoxy group include a methoxy group, an ethoxygroup, a propoxy group, an isopropoxy group, a butoxy group, anisobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxygroup and a hexyloxy group, and a C1-C4 alkoxy group is preferable and aC1-C2 alkoxy group is more preferable and a methoxy group is especiallypreferable.

Examples of the C2-C4 acyl group include an acetyl, group, a propionylgroup and a butyryl group, and examples of the C2-C4 acyloxy groupinclude an acetyloxy group, a propionyloxy group and a butyryloxy group.

Examples of the hydrocarbon group include the chain aliphatichydrocarbon group described above, the alicyclic hydrocarbon groupdescribed above, and the groups formed by combining these groups such as2-alkyl-2-adamantyl group and 1-(1-adamantyl)-1-alkyl group, and thearomatic hydrocarbon group.

Preferable examples of the hydrocarbon group represented by R^(a34) andR^(a35) include an isopropyl group, a butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, an octyl group, a2-ethylhexyl group, a cyclohexyl group, an adamantyl group, a2-alkyl-2-adamantyl group, a 1-(1-adamantyl)-1-alkyl group and anisobornyl group.

Preferable examples of the substituents in the C1-C17 divalent saturatedhydrocarbon group and the C1-C18 hydrocarbon group is a hydroxyl group.

Examples of the C1-C17 divalent aliphatic hydrocarbon group include aC1-C17 alkanediyl group such as a methylene group, an ethylene group, apropane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup, a undecane-1,11-diyl group, a dodecane-1,12-diyl group, atridecane-1,13-diyl group, a tetradecane-1,14-diyl group, apentadecane-1,15-diyl group, a hexadecane-1,16-diyl group and aheptadecane-1,17-diyl group.

Examples of the monomer represented by the formula (a1-4) include thefollowings.

Examples of the monomer represented by the formula (a1-4) include theabove-mentioned monomers wherein the following partial structure V′ isreplaced by the partial structure P′.

When RESIN (A) contains the structural unit derived form the monomerrepresented by the formula (a1-4), the content of the structural unitderived from the monomer represented by the formula (a1-4) is usually 10to 95% by mole and preferably 15 to 90% by mole and more preferably 20to 85% by mole based on total molar of all the structural units of RESIN(A).

Other examples of the monomer having an acid-labile group include amonomer represented by the formula (a1-5):

wherein R³¹ represents a hydrogen atom, a halogen atom, a C1-C4 alkylgroup which may be substituted with a halogen atom, L³¹ represents —O—,—S— or *—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, *represents a binding position to —CO—, L³² and L³³ independently eachrepresent —O— or —S—, Z¹ represents a single bond or a C1-C6 alkandiylgroup in which one or more —CH₂— may be replaced by —O— or —CO—, s1 ands2 independently each represent an integer of 0 to 4.

R³¹ is preferably a hydrogen atom or a methyl group.

L³¹ is preferably —O—.

It is preferred that one of L³² and L³³ is —O— and the other is —S—.

In the formula (a1-5), s1 is preferably 1 and s2 is preferably 0, 1 or2.

Z¹ is preferably a single bond or —CH₂—CO—O—.

Examples of the monomer represented by the formula (a1-5) include thefollowing.

When RESIN (A) contains the structural unit derived form the monomerrepresented by the formula (a1-5), the content of the structural unitderived from the monomer represented by the formula (a1-5) is usually 10to 95% by mole and preferably 10 to 90% by mole and more preferably 10to 85% by mole, and especially preferably 10 to 70% by mole based ontotal molar of all the structural units of RESIN (A).

RESIN (A) can have two or more kinds of structural units derived fromthe monomers having an acid-labile group.

RESIN (A) preferably contains the structural unit derived from themonomer having an acid-labile group and a structural unit derived fromthe monomer having no acid-labile group. RESIN (A) can have two or morekinds of structural units derived from the monomers having noacid-labile group. When RESIN (A) contains the structural unit derivedfrom the monomer having an acid-labile group and the structural unitderived from the monomer having no acid-labile group, the content of thestructural unit derived from the monomer having an acid-labile group isusually 10 to 80% by mole and preferably 20 to 60% by mole based ontotal molar of all the structural units of RESIN (A). The content of thestructural unit derived from a monomer having an adamantyl group,especially the monomer represented by the formula (a1-1) in thestructural unit derived from the compound having no acid-labile group ispreferably 15% by mole or more from the viewpoint of dry-etchingresistance of the photoresist composition.

The monomer having no acid-labile group preferably contains one or morehydroxyl groups or a lactone ring. When the resin contains thestructural unit derived from the monomer having no acid-labile group andhaving one or more hydroxyl groups or a lactone ring, a photoresistcomposition having good resolution and adhesiveness of photoresist to asubstrate tends to be obtained.

Examples of the structural unit derived from the monomer having noacid-labile group and having one or more hydroxyl groups include thestructural unit represented by the formula (a2-0):

wherein R^(a30) represents a hydrogen atom, a halogen atom, a C1-C6alkyl group or a C1-C6 halogenated alkyl group, R^(a31) is independentlyin each occurrence a halogen atom, a hydroxyl group, a C1-C6 alkylgroup, a C1-C6 alkoxy group, a C2-C4 acyl group, a C2-C4 acyloxy group,an acryloyl group or a methacryloyl group, ma represents an integer of 0to 4, andthe structural unit represented by the formula (a2-1):

wherein R^(a14) represents a hydrogen atom or a methyl group, R^(a15)and R^(a16) each independently represent a hydrogen atom, a methyl groupor a hydroxyl group, L^(a3) represents *—O— or *—O—(CH₂)_(k2)—CO—O— inwhich * represents a binding position to —CO—, and k2 represents aninteger of 1 to 7, and o1 represents an integer of 0 to 10.

When KrF excimer laser (wavelength: 248 nm) lithography system, or ahigh energy laser such as electron beam and extreme ultraviolet is usedas an exposure system, the resin containing the structural unit derivedfrom the monomer represented by the formula (a2-0) is preferable, andwhen ArF excimer laser (wavelength: 193 nm) is used as an exposuresystem, the resin containing the structural unit derived from themonomer represented by the formula (a2-1) is preferable.

In the formula (a2-0), examples of the halogen atom include a fluorineatom, examples of the C1-C6 alkyl group include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, an isobutylgroup, a sec-butyl group, a tert-butyl group, a pentyl group and a hexylgroup, and a C1-C4 alkyl group is preferable and a C1-C2 alkyl group ismore preferable and a methyl group is especially preferable. Examples ofthe C1-C6 halogenated alkyl group include a trifluoromethyl group, apentafluoroethyl group, a heptafluoropropyl group, aheptafluoroisopropyl group, a nonafluorobutyl group, anonafluoro-sec-butyl group, a nonafluoro-tert-butyl group, aperfluoropentyl group and a perfluorohexyl group. Examples of the C1-C6alkoxy group include a methoxy group, an ethoxy group, a propoxy group,an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxygroup, a tert-butoxy group, a pentyloxy group and a hexyloxy group, anda C1-C4 alkoxy group is preferable and a C1-C2 alkoxy group is morepreferable and a methoxy group is especially preferable. Examples of theC2-C4 acyl group include an acetyl group, a propionyl group and abutyryl group, and examples of the C2-C4 acyloxy group include anacetyloxy group, a propionyloxy group and a butyryloxy group. In theformula (a2-0), ma is preferably 0, 1 or 2, and is more preferably 0 or1, and especially preferably 0.

RESIN (A) containing the structural unit derived from the monomerrepresented by the formula (a2-0) can be produced, for example, bypolymerizing a monomer obtained by protecting a hydroxyl group of themonomer represented by the formula (a2-0) with a protecting group suchas an acetyl group followed by conducting deprotection of the obtainedpolymer with an acid or a base.

Examples of the monomer represented by the formula (a2-0) include thefollowings.

Examples of the monomer represented by the formula (a2-0) include theabove-mentioned monomers wherein a methyl group or an ethyl groupbonding to a benzene ring is replaced by the other substituent.

Among them, preferred are 4-hydroxystyrene and4-hydroxy-α-methylstyrene.

When RESIN (A) contains the structural unit represented by the formula(a2-0), the content of the structural unit represented by the formula(a2-0) is usually 5 to 95% by mole and preferably 10 to 80% by mole andmore preferably 15 to 80% by mole based on total molar of all thestructural units of RESIN (A).

In the formula (a2-1), R^(a14) is preferably a methyl group, R^(a15) ispreferably a hydrogen atom, R^(a16) is preferably a hydrogen atom or ahydroxyl group, L^(a3) is preferably *—O— or *—O—(CH₂)_(f2)—CO—O— inwhich * represents a binding position to —CO—, and f2 represents aninteger of 1 to 4, and is more preferably *—O— or *—O—CH₂—CO—O—, andespecially preferably *—O—, and of is preferably 0, 1, 2 or 3 and ismore preferably 0 or 1.

Examples of the structural unit represented by the formula (a2-1)include the structural units represented by the formulae (a2-1-1) to(a2-1-17).

Examples of the structural unit represented by the formula (a2-1)include the structural units represented by the formulae (a2-1-1) to(a2-1-17) wherein the partial structure M described above is replaced bythe partial structure A1 described above.

Among them, preferred are the structural units represented by theformulae (a2-1-1), (a2-1-2), (a2-1-13) and (a2-1-15) and thesestructural units wherein the partial structure M described above isreplaced by the partial structure A1 described above, and more preferredare the structural units represented by the formulae (a2-1-1), (a2-1-2),(a2-1-13) and (a2-1-15).

These structural unit can be derived from 3-hydroxy-1-adamantylacrylate, 3-hydroxy-1-adamantyl methacrylate, 3,5-dihydroxy-1-adamantylacrylate, 3,5-dihydroxy-1-adamantyl methacrylate,1-(3,5-dihydroxy-1-adamantyloxycarbonyl)methyl acrylate,1-(3,5-dihydroxy-1-adamantyloxycarbonyl)methylmethacrylate, and thelike.

When RESIN (A) contains the structural unit represented by the formula(a2-1), the content of the structural unit represented by the formula(a2-1) is usually 3 to 40% by mole based on total molar of all thestructural units of RESIN (A), and preferably 3 to 35% by mole, and morepreferably 3 to 30% by mole, and especially preferably 3 to 15% by mole.

Examples of the lactone ring of the monomer having no acid-labile groupand a lactone ring include a monocyclic lactone ring such asβ-propiolactone ring, γ-butyrolactone ring and γ-valerolactone ring, anda condensed ring formed from a monocyclic lactone ring and the otherring. Among them, preferred are γ-butyrolactone ring and a condensedlactone ring formed from γ-butyrolactone ring and the other ring.

Preferable examples of the structural unit derived from the monomerhaving no acid-labile group and a lactone ring include the structuralunits represented by the formulae (a3-1), (a3-2) and (a3-3):

wherein L^(a4), L^(a5) and L^(a6) each independently represent *—O— or*—O— (CH₂)_(k3)—CO—O— in which * represents a binding position to —CO—and k3 represents an integer of 1 to 7, R^(a18), R^(a19) and R^(a20)each independently represent a hydrogen atom or a methyl group, R^(a21)represents a C1-C4 aliphatic hydrocarbon group, R^(a22) and R^(a23) areindependently in each occurrence a carboxyl group, a cyano group or aC1-C4 aliphatic hydrocarbon group, and p1 represents an integer of 0 to5, q1 and r1 independently each represent an integer of 0 to 5.

It is preferred that L^(a4), L^(a5) and L^(a6) each independentlyrepresent *—O— or *—O—(CH₂)_(d1)—CO—O— in which * represents a bindingposition to —CO— and d1 represents an integer of 1 to 4, and it is morepreferred that L^(a4), L^(a5) and L^(a6) are *—O— or *—O—CH₂—CO—O—, andit is especially preferred that L^(a4), L^(a5) and L^(a6) are *—O—.R^(a18), R^(a19) and R^(a20) are preferably methyl groups. R^(a21) ispreferably a methyl group. It is preferred that R^(a22) and R^(a23) areindependently in each occurrence a carboxyl group, a cyano group or amethyl group. It is preferred that p1 is an integer of 0 to 2, and it ismore preferred that p1 is 0 or 1. It is preferred that q1 and r1independently each represent an integer of 0 to 2, and it is morepreferred that q1 and r1 independently each represent 0 or 1.

Examples of the structural unit represented by the formula (a3-1)include the structural units represented by the formulae (a3-1-1) to(a3-1-11).

Examples of the structural unit represented by the formula (a3-2)include the structural unit represented by the formula (a2-2-1) to(a3-2-11).

Examples of the structural unit represented by the formula (a3-3)include the structural unit represented by the formula (a3-3-1) to(a3-3-6).

Examples of the structural unit represented by the formula (a3-3)include the structural unit represented by the formula (a3-1-1) to(a3-1-11), (a3-2-1) to (a3-2-11) and (a3-3-1) to (a3-3-6) wherein thepartial structure M described above is replaced by the partial structureA1 described above.

Among them, preferred are the structural units derived fromα-acryloyloxy-γ-butyrolactone, α-methacryloyloxy-γ-butyrolactone,β-acryloyloxy-γ-butyrolactone, β-methacryloyloxy-γ-butyrolactone,α-acryloyloxy-β,β-dimethyl-γ-butyrolactone,α-methacryloyloxy-β,β-dimethyl-γ-butyrolactone,α-acryloyloxy-α-methyl-γ-butyrolactone,α-methacryloyloxy-α-methyl-γ-butyrolactone,β-acryloyloxy-α-methyl-γ-butyrolactone,β-methacryloyloxy-α-methyl-γ-butyrolactone,5-oxo-4-oxatricyclo[4.2.1.0^(3,7)]nonan-2-yl acrylate,5-oxo-4-oxatricyclo[4.2.1.0^(3,7)]nonan-2-yl methacrylate,tetrahydro-2-oxo-3-furyl acrylate, tetrahydro-2-oxo-3-furylmethacrylate,2-(5-oxo-4-oxatricyclo[4.2.1.0^(3,7)]nonan-2-yloxy)-2-oxoethyl acrylateand 2-(5-oxo-4-oxatricyclo[4.2.1.0^(3,7)]nonan-2-yloxy)-2-oxoethylmethacrylate.

When RESIN (A) contains the structural unit derived from the monomerhaving no acid-labile group and having a lactone ring, the contentthereof is usually 5 to 70% by mole based on total molar of all thestructural units of RESIN (A), and preferably 10 to 65% by mole and morepreferably 10 to 60% by mole, still more preferably 15 to 55% by moleand especially preferably 15 to 50% by mole.

When RESIN (A) contains the structural unit represented by the formula(a3-1), (a3-2) or (a3-3), the content thereof is usually 5 to 70% bymole based on total molar of all the structural units of RESIN (A), andpreferably 10 to 65% by mole and more preferably 10 to 60% by mole,still more preferably 15 to 55% by mole and especially preferably 15 to50% by mole.

Examples of the other monomer having no acid-labile group include themonomers represented by the formulae (a4-1), (a4-2) and (a4-3):

wherein R^(a25) and R^(a26) each independently represents a hydrogenatom, a C1-C3 alkyl group which can have one or more hydroxyl groups, acarboxyl group, a cyano group or a —COOR^(a27) group in which R^(a27)represents a C1-C18 aliphatic hydrocarbon group, and one or more —CH₂—in the C1-C18 aliphatic hydrocarbon group can be replaced by —O— or—CO—, with the proviso that the carbon atom bonded to —O— of —COO— ofR^(a27) is not a tertiary carbon atom, or R^(a25) and R^(a26) are bondedtogether to form a carboxylic anhydride residue represented by—C(═O)—O—C(═O)—.

Examples of the substituent of the C1-C3 alkyl group include a hydroxylgroup. Examples of the C1-C3 alkyl group which can have one or morehydroxyl groups include a methyl group, an ethyl group, a propyl group,a hydroxymethyl group and a 2-hydroxyethyl group. The C1-C18 aliphatichydrocarbon group represented by R^(a27) is preferably a C1-C8 alkylgroup or C4-C18 alicyclic hydrocarbon group and is more preferably aC1-C6 alkyl group cc a C4-C12 alicyclic hydrocarbon group. Preferableexamples of R^(a27) include a methyl group, an ethyl group, a propylgroup, a 2-oxo-oxolan-3-yl group and a 2-oxo-oxolan-4-yl group.

Examples of the monomer represented by the formula (a4-3) include2-norbornene, 2-hydroxy-5-norbornene, 5-norbornene-2-carboxylicacid,methyl 5-norbornene-2-carboxylate, 2-hydroxyethyl5-norbornene-2-carboxylate, 5-norbornene-2-methanol and5-norbornene-2,3-dicarboxylic anhydride.

When RESIN (A) contains a structural unit derived from a monomerrepresented by the formula (a4-1), (a4-2) or (a4-3), the content thereofis usually 2 to 40% by mole and preferably 3 to 30% by mole and morepreferably 5 to 20% by mole based on total molar of all the structuralunits of RESIN (A).

Examples of the other monomer having no acid-labile group include thefluorine-containing monomers represented by the following formulae.

Among them, preferred are5-(3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl)bicyclo[2.2.1]hept-2-ylacrylate,5-(3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl)bicyclo[2.2.1]hept-2-ylmethacrylate,6-(3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl)bicyclo[2.2.1]hept-2-ylacrylate,5-(3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl)bicyclo[2.2.1]hept-2-ylmethacrylate, 4,4-bis(trifluoromethyl)-3-oxatricyclo[4.2.1.0^(2,5)]nonylacrylate and 4,4-bis(trifluoromethyl)-3-oxatricyclo[4.2.1.0^(2,5)]nonylmethacrylate.

When RESIN (A) contains a structural unit derived from theabove-mentioned fluorine-containing monomer, the content thereof isusually 1 to 20% by mole based on total molar of all the structuralunits of RESIN (A), and preferably 2 to 15% by mole and more preferably3 to 10% by mole.

Examples of the other monomer having no acid-labile group include themonomers having a group represented by the formula (3):

wherein R¹⁰ represents a C1-C6 fluorinated alkyl group, in its sidechain.

Examples of the C1-C6 fluorinated alkyl group include a difluoromethylgroup, a trifluoromethyl group, a 1,1-difluoroethyl group, a2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a perfluoroethylgroup, a 1,1,2,2-tetrafluoropropyl group, a 1,1,2,2,3,3-hexafluoropropylgroup, a (perfluoroethyl)methyl group, a1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl group, a perfluoropropylgroup, a 1,1,2,2-tetrafluorobutyl group, a 1,1,2,2,3,3-hexafluorobutylgroup, a 1,1,2,2,3,3,4,4-octafluorobutyl group, a perfluorobutyl group,a 1,1-bis(trifluoromethyl)-2,2,2-trifluoroethyl group,2-(perfluoropropyl)ethyl group, a 1,1,2,2,3,3,4,4-octafluoropentylgroup, a perfluoropentyl group, a 1,1,2,2,3,3,4,4,5,5-decafluoropentylgroup, a 1,1-bis(trifluoromethyl)-2,2,3,3,3,-pentafluoropropyl group, aperfluoropentyl group, a 2-(perfluorobutyl)ethyl group, a1,1,2,2,3,3,4,4,5,5-decafluorohexyl group, a1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl group, a(perfluoropentyl)methyl group and a perfluorohexyl group. Among thempreferred is a C1-C4 fluorinated alkyl group, and more preferred are atrifluoromethyl group, a perfluoroethyl group and a perfluoropropylgroup, and especially preferred is a trifluoromethyl group.

Examples of the monomer having the group represented by the formula (3)in its side chain include the following.

When RESIN (A) contains a structural unit derived from theabove-mentioned monomer having the group represented by the formula (3)in its side chain, the content thereof is usually 1 to 30% by mole basedon total molar of all the structural units of RESIN (A), and preferably3 to 25% by mole and more preferably 5 to 20% by mole.

Examples of the other monomer having no acid-labile group include themonomers having a group represented by the formula (4):

wherein R¹¹ represents a C6-C12 aromatic hydrocarbon group which mayhave one or more substituents, R¹² represents a C1-C12 hydrocarbon groupwhich may have one or more substituents and which may contain one ormore heteroatoms, and A² represents a single bond, —(CH₂)_(m)—SO₂—O—* or—(CH₂)_(m)—CO—O—* in which one or more —CH₂— may be replaced by —O—,—CO— or —SO₂— and in which one or more hydrogen atoms may be replaced bya fluorine atom, and m represents an integer of 1 to 12, in its sidechain.

Examples of the C6-C12 aromatic hydrocarbon group include a phenylgroup, a biphenyl group, a fluorenyl group, a naphthyl group and ananthryl group.

Examples of the substituents of the aromatic hydrocarbon group include aC1-C4 alkyl group such as a methyl group, an ethyl group, a propylgroup, an isopropyl group, a butyl group, an isobutyl group and atert-butyl group, a halogen atom such as a fluorine atom, a chlorineatom and a bromine atom, a phenyl group, a nitro group, a cyano group, ahydroxyl group, a phenoxy group and a tert-butylphenyl group.

Examples of R¹¹ include the following. In the following formulae, *represents a binding position to —C(R¹²)═N.

Examples of the C1-C12 hydrocarbon group include a C1-C12 chainaliphatic hydrocarbon group, a C3-C12 alicyclic hydrocarbon group and aC6-C12 aromatic hydrocarbon group. Examples of the C1-C12 chainaliphatic hydrocarbon group include a linear aliphatic hydrocarbon groupsuch as a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, a decyl group, an undecyl group and a dodecyl group, and abranched chain aliphatic hydrocarbon group such as an isopropyl group, asec-butyl group, a tert-butyl group, a methylpentyl group, anethylpentyl group, a methylhexyl group, an ethylhexyl group, apropylhexyl group and a tert-octyl group. Preferred is a branched chainaliphatic hydrocarbon group, and more preferred are an isopropyl group,a sec-butyl group, a tert-butyl group and an ethylhexyl group.

Examples of the C3-C12 alicyclic hydrocarbon group include thefollowing. In the following formulae, * represents a binding position to—C(R¹¹)═N.

The C1-C12 hydrocarbon group may contain one or more heteroatoms such asa halogen atom, a sulfur atom, an oxygen atom and a nitrogen atom, andit may also contain a group formed by combining two or more heteroatomssuch as —SO₂— and —CO—. Examples of the C1-C12 hydrocarbon groupcontaining one or more heteroatoms include the following.

Examples of the C6-C12 aromatic hydrocarbon group include the same asthose of R¹¹.

Examples of A² include the following.

wherein * represents a binding position to —N═C(R¹¹) (R¹²).

In the above-mentioned formulae, the group represented by the formula(A²-1) represents a single bond.

Preferable examples of the monomer having the group represented by theformula (4) include a monomer represented by the formula (a6-1):

wherein A², R¹¹ and R¹² are the same as defined above, and R¹³represents a hydrogen atom or a methyl group.

Examples of the monomer represented by the formula (a6-1) include thefollowing.

Examples of the monomer represented by the formula (a6-1) include theabove-mentioned monomers wherein the partial structure P′ describedabove is replaced by the partial structure V′ described above.

When RESIN (A) contains a structural unit derived from theabove-mentioned monomer having the group represented by the formula (4)in its side chain, the content thereof is usually 1 to 30% by mole basedon total molar of all the structural units of RESIN (A), and preferably3 to 25% by mole and mare preferably 5 to 20% by mole.

Examples of the other monomer having no acid-labile group include themonomers represented by the formula (a4-7):

wherein R¹⁴ represents a hydrogen atom, a halogen atom, a C1-C6 alkylgroup or a C1-C6 haloalkyl group, A⁴ represents a single bond or aC1-C17 divalent aliphatic hydrocarbon group in which one or more —CH₂—other than —CH₂— bonded to R¹⁴—C(═CH₂)—CO—O— can be replaced by —O— or—CO—, ring W² represents a C3-C36 aliphatic ring, R¹⁵ and R¹⁶ eachindependently represent a C1-C6 alkyl group a C1-C6 haloalkyl group.

The C3-C36 aliphatic ring may be a monocyclic ring or a polycyclic ring.Preferred is a C5-C18 aliphatic ring, and more preferred is a C6-C12aliphatic ring. Examples thereof include the above-mentioned aliphaticrings represented by the formulae (KA-1) to (KA-22), and a cyclohexanering, an adamantane ring, a norbornane ring and a norbornene ring arepreferable.

Examples of the C1-C17 divalent aliphatic hydrocarbon group in clued thesame as described above. The C1-C17 divalent aliphatic hydrocarbon groupmay have one or more substituents. The C1-C17 divalent aliphatichydrocarbon group includes the above-mentioned alkanediyl group, theabove-mentioned divalent alicyclic hydrocarbon group, and the groupformed by combining the above-mentioned alkanediyl group and theabove-mentioned divalent alicyclic hydrocarbon group.

Examples of the group formed by combining the above-mentioned alkanediylgroup and the above-mentioned divalent alicyclic hydrocarbon groupinclude the following groups represented by the formulae (X^(X)-A),(X^(X)—B) and (X^(X)—C):

wherein X^(X1) and X^(X2) each independently represent a single bond ora C1-C6 alkylene group optionally substituted, with the proviso thatX^(X1) and X^(X2) are not single bonds at the same time, and the totalcarbon number of each of the groups represented by the formulae(X^(X)-A), (X^(X)—B) and (X^(X)—C) is 17 or less.

A⁴ is preferably a single bond or *—(CH₂)_(s1)—CO—O— in which *represents a binding position to —O— and s1 represents an integer of 1to 6, and more preferably a single bond or *—CH₂—CO—O—.

Examples of the C1-C6 alkyl group include the same as described above,and examples of the C1-C6 haloalkyl group include a fluorinated alkylgroup such as a trifluoroalkyl group, a perfluoroethyl group, aperfluoropropyl group and a perfluorobutyl group, and a trifluoroalkylgroup, a perfluoroethyl group and a perfluoropropyl group arepreferable.

R¹⁴ is preferably a hydrogen atom or a methyl group.

Examples of the monomer represented by the formula (aa-4-7) include thefollowing.

Among them, preferred are the following monomers.

Specific examples thereof include the following and the followingmonomers wherein the above-mentioned partial structure P′ is replaced bythe above-mentioned partial structure V′.

The monomer represented by the formula (a4-7) can be produced byreacting a compound represented by the formula (a4-7-a) with a compoundrepresented by the formula (a4-7-b).

Examples of the compound represented by the formula (a4-7-a) include1-methacryloyloxy-4-oxoadamantane described in JP 2002-226436 A.Examples of the compound represented by the formula (a4-7-b) includepentafluoropropionic anhydride, heptafluorobutyric anhydride andtrifluoroacetic anhydride.

The reaction is preferably conducted at the temperature nearly to theboiling point of the compound represented by the formula (a4-7-b).

When RESIN (A) contains a structural unit derived from theabove-mentioned monomer represented by the formula (a4-7), the contentthereof is usually 1 to 30% by mole based on total molar of all thestructural units of RESIN (A), and preferably 3 to 25% by mole and morepreferably 5 to 20% by mole.

Preferable RESIN (A) is a resin comprising the unit represented by theformula (aa), the structural unit derived from the monomer having anacid-labile group and the structural unit derived from the monomerhaving no acid-labile group, and more preferable RESIN (A) is a resincomprising the unit represented by the formula (aa), the structural unitderived from the monomer having an acid-labile group and the structuralunit derived from the monomer having one or more hydroxyl groups and/orthe monomer having a lactone ring. The structural unit derived from themonomer having an acid-labile group is preferably the structural unitrepresented by the formula (a1-1) or (a1-2), and is more preferably thestructural unit represented by the formula (a1-1). The structural unitderived from the monomer having one or more hydroxyl groups ispreferably the structural unit represented by the formula (a2-1), andthe structural unit derived from the monomer having a lactone ring ispreferably the structural unit represented by the formula (a3-1) or(a3-2).

RESIN (A) can be produced according to known polymerization methods suchas radical polymerization.

RESIN (A) usually has 2,500 or more of the weight-average molecularweight, preferably 3,000 or more of the weight-average molecular weight.RESIN (A) usually has 50,000 or less of the weight-average molecularweight, preferably has 30,000 or less of the weight-average molecularweight. The weight-average molecular weight can be measured with gelpermeation chromatography.

The content of RESIN (A) in the photoresist composition of the presentinvention is usually 60% by mass or more based on sum of solidcomponent, and usually 99% by mass or less. In this specification,“solid component” means components other than solvent in the photoresistcomposition.

The photoresist composition of the present invention contains an acidgenerator, and can contain two or more kinds of the acid generators.

The acid generator is a substance which is decomposed to generate anacid by applying a radiation such as a light, an electron beam or thelike on the substance itself or on a photoresist composition containingthe substance. The acid generated from the acid generator acts on theresin resulting in cleavage of the acid-labile group existing in theresin.

Examples of the acid generator include a nonionic acid generator, anionic acid generator and the combination thereof. Examples of thenonionic acid generator include an organo-halogen compound, a sulfonecompound such as a disulfone, a ketosulfone and a sulfonyldiazomethane,a sulfonate compound such as a 2-nitrobenzylsulfonate, an aromaticsulfonate, an oxime sulfonate, an N-sulfonyloxyimide, asulfonyloxyketone and diazonaphthoquinone 4-sulfonate. Examples of theionic acid generator include an onium salt compound such as a diazoniumsalt, a phosphonium salt, a sulfonium salt and an iodonium salt .Examples of the anion of the onium salt include a sulfonic acid anion, asulfonylimide anion and a sulfonulmethide anion. The onium salt compoundis preferable.

Other examples of the acid generator include acid, generators describedin JP 63-26653 A, JP 55-164824 A, JP 62-69263 A, JP 63-146038 A, JP63-163452 A, JP 62-153853 A, JP 63-146029 A, U.S. Pat. No. 3,779,778,U.S. Pat. No. 3,849,137, DE Patent No. 3914407 and EP Patent No.126,712.

A fluorine-containing acid generator is preferable.

Preferable examples of the acid generator include a salt represented bythe formula (B1):

wherein Q¹ and Q² each independently represent a fluorine atom or aC1-C6 perfluoroalkyl group,L^(b1) represents a single bond or a C1-C17 divalent aliphatichydrocarbon group which can have one or more substituents, and one ormore —CH₂— in the divalent aliphatic hydrocarbon group can be replacedby —O— or —CO—,Y represents a C1-C18 aliphatic hydrocarbon group which can have one ormore substituents and in which one or more —CH₂— can be replaced by —O—,—CO— or —SO₂—, andZ⁺ represents an organic cation.

Examples of the C1-C6 perfluoroalkyl group include a trifluoromethylgroup, a pentafluoroethyl group, a heptafluoropropyl group, anonafluorobutyl group, an undecafluoropentyl group and atridecafluorohexyl group, and a trifluoromethyl group is preferable. Q¹and Q² each independently preferably represent a fluorine atom or atrifluoromethyl group, and Q¹ and Q² are more preferably fluorine atoms.

Examples of the C1-C17 divalent aliphatic hydrocarbon group include aC1-C17 alkandiyl group, a monocyclic or polycyclic divalent saturatedhydrocarbon group and a group formed by combining two or more groupsselected from the group consisting of a C1-C17 alkandiyl group and amonocyclic or polycyclic divalent saturated hydrocarbon group.

Examples thereof include a linear alkanediyl group such as a methylenegroup, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diylgroup, a pentane-1,5-diyl, a hexane-1,6-diyl group, a heptane-1,7-diylgroup, an octane-1,8-diyl group, a nonane-1,9-diyl group, adecane-1,10-diyl group, an undecane-1,11-diyl group, adodecane-1,12-diyl group, a tridecane-1,13-diyl group, atetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, ahexadecane-1,16-diyl group and a heptadecane-1,17-diyl group, a branchedchain alkanediyl group such as a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group and a 2-methylbutane-1,4-diyl group, a monocyclicdivalent saturated hydrocarbon group such as a cyclobutane-1,3-diylgroup, a cyclopentane-1,3-diyl group, a cyclohexane-1,2-diyl group, a1-methylcyclohexane-1,2-diyl group, a cyclohexane-1,4-diyl group, acyclooctane-1,2-diyl group and a cyclooctane-1,5-diyl group, and apolycyclic divalent saturated hydrocarbon group such as anorbornane-2,3-diyl group, a norbornane-1,4-diyl group, anorbornane-2,5-diyl group, an adamantane-1,2-diyl group, anadamantane-1,5-diyl group and an adamantane-2,6-diyl group.

Examples of the C1-C17 aliphatic hydrocarbon group in which one or more—CH₂— are replaced by —O— or —CO— include *—CO—O-L^(b2),*—CO—O-L^(b4)-CO—O-L^(b3)-, *-L^(b5)-O—CO—, *-L^(b7)-O-L^(b6)-,*—CO—O-L^(b8)-O—, and *—CO—O-L^(b10)-O-L^(b9)-CO—O—, wherein L^(b2)represents a single bond or a C1-C15 aliphatic hydrocarbon group, L^(b3)represents a single bond or a C1-C12 aliphatic hydrocarbon group, L^(b4)represents a single band or a C1-C13 aliphatic hydrocarbon group, withproviso that total carbon number of L^(b3) and L^(b4) is 1 to 13, L^(b5)represents a C1-C15 aliphatic hydrocarbon group, L^(b6) represents aC1-C15 aliphatic hydrocarbon group, L^(b7) represents a C1-C15 aliphatichydrocarbon group, with proviso that total carbon number of L^(b6) andL^(b7) is 1 to 16, L^(b8) represents a C1-C14 aliphatic hydrocarbongroup, L^(b9) represents a C1-C11 aliphatic hydrocarbon group, L^(b10)represents a C11-C11 aliphatic hydrocarbon group, with proviso thattotal carbon number of L^(b9) and L^(b10) is 1 to 12, and * represents abinding position to —C(Q¹)(Q²)-.

The aliphatic hydrocarbon group is preferably a saturated aliphatichydrocarbon.

Among them, preferred is *—CO—O-L^(b2)-, and more preferred is*—CO—O-L^(b2)- in which L^(b2) is a single bond or —CH₂—.

Examples of *—CO—O-L^(b2)- include *—CO—O— and *—CO—O—CH₂—. Examples of*—CO—O-L^(b4)-CO—O-L^(b3)- include *—CO—O—CH₂—CO—O—,*—CO—O—(CH₂)₂—CO—O—, *—CO—O—(CH₂)₃—CO—O—, *—CO—O—(CH₂)₄—CO—O—,*—CO—O—(CH₂)₆—CO—O—, *—CO—O—(CH₂)₈—CO—O—, *—CO—O—CH₂—CH(CH₃)—CO—O— and*—CO—O—CH₂—C(CH₃)₂—CO—O—. Examples of *-L^(b5)-O—CO— include*—CH₂—O—CO—, *—(CH₂)₂—O—CO—, *—(CH₂)₃—O—CO—, *—(CH₂)₄—O—CO—,*—(CH₂)₆—O—CO— and *—(CH₂)₈—O—CO—. Examples of *-L^(b7)-O-L^(b6)-include *—CH₂—O—CH₂—. Examples of *—CO—O-L^(b8)-O— include*—CO—O—CH₂—O—, *—CO—O—(CH₂)₂—O—, *—CO—O—(CH₂)₃—O—, *—CO—O—(CH₂)₄—O— and*—CO—O—(CH₂)₆—O—. Examples of *—CO—O-L^(b10)-O-L^(b9)-CO—O— include thefollowings.

Examples of the substituent in Y include a halogen atom other than afluorine atom, a hydroxyl group, an oxo group, a glycidyloxy group, aC2-C4 acyl group, a C1-C12 alkoxy group, a C2-C7 alkoxycarbonyl group, aC1-C12 aliphatic hydrocarbon group, a C1-C12 hydroxy-containingaliphatic hydrocarbon group, a C3-C16 saturated cyclic hydrocarbongroup, a C6-C18 aromatic hydrocarbon group, a C7-C21 aralkyl group and—(CH₂)_(j2)—O—CO—R^(b1)— in which R^(b1) represents a C1-C16 aliphatichydrocarbon group, a C3-C16 saturated cyclic hydrocarbon group or aC6-C18 aromatic hydrocarbon group and j2 represents an integer of 0 to4. Examples of the halogen atom include a chlorine atom, a bromine atomand an iodine atom. Examples of the acyl group include an acetyl groupand a propionyl group, and examples of the alkoxy group include amethoxy group, an ethoxy group, a propoxy group, an isopropoxy group anda butoxy group. Examples of the alkoxycarbonyl group include amethoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group,an isopropoxycarbonyl group and a butoxycarbonyl group. Examples of thealiphatic hydrocarbon group include the same as described above.Examples of the hydroxyl-containing aliphatic hydrocarbon group includea hydroxymethyl group. Examples of the C3-C16 saturated cyclichydrocarbon group include the same as described above, and examples ofthe aromatic hydrocarbon group include a phenyl group, a naphthyl group,an anthryl group, a p-methylphenyl group, a p-tert-butylphenyl group anda p-adamantylphenyl group. Examples of the aralkyl group include abenzyl group, a phenethyl group, a phenylpropyl group, a trityl group, anaphthylmethyl group and a naphthylethyl group.

The C1-C18 aliphatic hydrocarbon group represented by Y includes a chainaliphatic hydrocarbon group and an alicyclic hydrocarbon group. Y ispreferably an alkyl group or an alicyclic hydrocarbon group, and morepreferably a C1-C6 alkyl group or a C3-C12 alicyclic hydrocarbon group,and especially preferably a C3-C12 alicyclic hydrocarbon group.

Examples of the C1-C18 aliphatic hydrocarbon group represented by Yinclude a methyl group, an ethyl group, a propyl group, an isopropylgroup, a butyl group, an isobutyl group, a sec-butyl group, a tert-butylgroup, a pentyl group, a neopentyl group, a 1-methylbutyl group, a2-methylbutyl group, a 1,2-dimethylpropyl group, a 1-ethylpropyl group,a hexyl group, a 1-methylpentyl group, a heptyl group, an octyl group, a2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group and adodecyl group.

Examples of the aliphatic hydrocarbon group in which one or more —CH₂—are replaced by —O—, —CO— or —SO₂— include a group having an etherstructure or a cyclic ether structure, a saturated cyclic hydrocarbongroup having an oxo group, a sultone ring group and a lactone ringgroup.

Preferable examples thereof include the groups represented by theformulae (Y1) to (Y5), and groups represented by the formulae (Y1),(Y2), (Y3) and (Y5) are more preferable and groups represented by theformulae (Y1) and (Y2) are especially preferable.

Examples of Y having one or more substituents include the followings:

Y is preferably an adamantyl group which can have one or moresubstituents, and is more preferably an adamantyl group or anhydroxyadamantyl group.

Among the sulfonic acid anions of the acid generator represented by theformula (B1), preferred is a sulfonic acid anion having *—CO—O-L^(b2)-,and more preferred are anions represented by the formulae (b1-1-1) to(b1-1-9).

wherein Q¹, Q² and L^(b2) are the same as defined above, and R^(b2) andR^(b3) each independently represent a C1-C4 aliphatic hydrocarbon groupand it is more preferred that R^(b2) and R^(b3) each independentlyrepresent a methyl group.

Examples of the anions represented by the formulae (b1-1-1) to (b1-1-9)include anions described in JP 2010-204646 A.

Specific examples of the sulfonic acid anion include the followings.

Examples of the organic counter ion represented by Z⁺ include an oniumcation such as a sulfonium cation, an iodonium cation, an ammoniumcation, a benzothiazolium cation and a phosphonium cation, and asulfonium cation and an iodonium cation are preferable, and a sulfoniumcation is more preferable.

Preferable examples of the organic counter ion represented by Z⁺ includethe organic cations represented by the formulae (b2-1) to (b2-4):

In the formulae (b2-1) to (b2-4) R^(b4), R^(b5) and R^(b6) independentlyrepresent a C1-C30 hydrocarbon group. As the C1-C30 hydrocarbon group, aC1-C30 alkyl group, a C3-C18 alicyclic hydrocarbon group and a 06-018aromatic hydrocarbon group are preferable. The alkyl group can have oneor more substituents selected from the group consisting of a hydroxylgroup, a C1-C12 alkoxy group and a C6-C18 aromatic hydrocarbon group.The C3-C18 alicyclic hydrocarbon group can have one or more substituentsselected from the group consisting of a halogen atom, a C2-C4 acyl groupand a glycidyloxy group. The C6-C18 aromatic hydrocarbon group can haveone or more substituents selected from the group consisting of a halogenatom, a hydroxyl group, a C1-C18 aliphatic hydrocarbon group, a C3-C18saturated cyclic hydrocarbon group and a C1-C12 alkoxy group.

R^(b7) and R^(b8) are independently in each occurrence a hydroxyl group,a C1-C12 alkyl group or a C1-C12 alkoxy group, m2 and n2 independentlyrepresents an integer of 0 to 5.

R^(b9) and R^(b10) independently represent a C1-C18 alkyl group or aC3-C18 alicyclic hydrocarbon group.

R^(b11) represents a hydrogen atom, a C1-C18 alkyl group, a C3-C18alicyclic hydrocarbon group or a C6-C18 aromatic hydrocarbon group.

When R^(b9), R^(b10) and R^(b11) each independently represent an alkylgroup, it is preferably a C1-C12 alkyl group, and when R^(b9), R^(b10)and R^(b11) each independently represent an alicyclic hydrocarbon group,it is preferably C3-C18 alicyclic hydrocarbon group and more preferablyC4-C12 alicyclic hydrocarbon group.

R^(b12) represents a C1-C18 hydrocarbon group and examples thereofinclude a C1-C18 aliphatic hydrocarbon group, a C3-C18 saturated cyclichydrocarbon group and a C6-C18 aromatic hydrocarbon group and thearomatic hydrocarbon group can have one or more substituents selectedfrom the group consisting of a C1-C12 aliphatic hydrocarbon group, aC1-C12 alkoxy group, a C3-C18 saturated cyclic hydrocarbon group and a(C1-C12 alkyl)carbonyloxy group.

R^(b9) and R^(b10) can be bonded to form a C2-C11 divalent acyclichydrocarbon group which forms a ring together with the adjacent S⁺, andone or more —CH₂— in the divalent acyclic hydrocarbon group may bereplaced by —CO—, —O— or —S—, and preferred is a C2-C6 divalent acyclichydrocarbon group.

R^(b11) and R^(b12) can be bonded each other to form a C1-C10 divalentacyclic hydrocarbon group which forms a 2-oxocycloalkyl group togetherwith the adjacent —CHCO—, and one or more —CH₂— in the divalent acyclichydrocarbon group may, be replaced by —CO—, —O— or —S—, and preferred isa C1-C5 divalent acyclic hydrocarbon group.

R^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) independentlyrepresent a hydroxyl group, a C1-C12 alkyl group or a C1-C12 alkoxygroup.

L^(b11) represents —S— or —O— and o2, p2, s2 and t2 each independentlyrepresents an integer of 0 to 5, q2 and r2 each independently representsan integer of 0 to 4, and u2 represents 0 or 1.

Preferable examples of the aliphatic hydrocarbon group represented byR^(b4) to R^(b6) include an alkyl group such as a methyl group, an ethylgroup, a propyl group, an isopropyl group, 2,2-dmethylethyl group,1-methylpropyl group, a 2-methylpropyl group, a 1,2-dimethylpropylgroup, a 2,2-dimethylpropyl group, a 1-ethylpropyl group, a butyl group,a sec-butyl group, a tert-butyl group, a pentyl group, a 1-methylbutylgroup, a 2-methylbutyl group, a 3-methylbutyl group, a hexyl group, a1-propylbutyl group, a 1-methylpentyl group, a 2-ethylhexyl group, a1,4-dimethylhexyl group, a 1-methylheptyl group, an octyl group, a decylgroup, a dodecyl group, a hexadecyl group, a pentadecyl group, aheptadecyl group and an octadecyl group, and more preferable examplesthereof include a methyl group, an ethyl group, a propyl group, anisopropyl group, a butyl group, a sec-butyl, group, a tert-butyl group,a pentyl group, a hexyl group, an octyl group and a 2-ethylhexyl group.

The saturated cyclic hydrocarbon group may be monocyclic or polycyclic.Preferable examples thereof include a cycloalkyl group such as acyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, adimethylcyclohexyl group, a cycloheptyl group and a cyclooctyl group, agroup obtained by hydrogenating a condensed aromatic hydrocarbon groupsuch as a hydronaphthyl group, a bridged cyclic hydrocarbon group suchas an adamantyl group, a norbornyl group and a methylnorbornyl group,and the following groups.

Among them, preferred are a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cyclodecyl group, a2-alkyl-2-adamantyl group, a 1-(1-adamantyl)alkan-1-yl group and anisobornyl group.

Preferable examples of the aromatic group include an aryl group such asa phenyl group, a naphthyl group, an anthryl group, a 4-methylphenylgroup, a 4-ethylphenyl group, a 4-tert-butylphenyl group, a4-cyclohexylphenyl group, a 4-methoxyphenyl group, a p-adamantylphenylgroup, a tolyl group, a xylyl group, a cumyl group, a mesityl group, abiphenyl group, a phenanthryl group, a 2,6-diethylphenyl group and a2-methyl-6-ethylphenyl group, and a phenyl group, a 4-methylphenylgroup, a 4-ethylphenyl group, a 4-tert-butylphenyl group, a4-cyclohexylphenyl group, a 4-methoxyphenyl group, a biphenyl group anda naphthyl group are more preferable.

Examples of the C1-C12 alkoxy group include a methoxy group, an ethoxygroup, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxygroup, a heptyloxy group, an octyloxy group, a decyloxy group and adodecyloxy group. Examples of the halogen atom include a fluorine atom,a chlorine atom, a bromine atom and an iodine atom. Examples of theC2-C4 acyl group include an acetyl group, a propyonyl group and abutyryl group.

Examples of the C3-C12 divalent acyclic hydrocarbon group formed bybonding R^(b9) and R^(b10) include a trimethylene group, atetramethylene group and a pentamethylene group. Examples of the ringgroup formed together with the adjacent S⁺ and the divalent acyclichydrocarbon group include a thian-1-ium ring (tetrahydrothipheniumring), a thian-1-ium ring and a 1,4-oxathian-4-ium ring. AC3-C7 divalentacyolic hydrocarbon group is preferable.

Examples of the C1-C10 divalent acyclic hydrocarbon group formed bybonding R^(b11) and R^(b12) include a methylene group, an ethylenegroup, a trimethylene group, a tetramethylene group and a pentamethylenegroup and examples of the ring group include the followings.

A C1-C5 divalent acyclic hydrocarbon group is preferable.

Examples of the C2-C13 acyloxy group include an acetyloxy group, apropyonyloxy group, a butyryloxy group, an isopropylcarbonyloxy group, abutylcarbonyloxy group, a sec-butylcarbonyloxy group, atert-butylcarbonyloxy group, a pentylcarbonyloxy group, ahexylcarbonyloxy group, an octylcarbonyloxy group and a2-ethylhexylcarbonyloxy group.

Examples of the cations represented by the formulae (b2-1) to (b2-4)include those described in JP 2010-204646 A.

Among the above-mentioned cations, preferred is the cation representedby the formula (b2-1), and more preferred is the cation represented bythe formula (b2-1-1). A triphenylsulfonium cation and a trytolysulfoniumcation are especially preferable.

wherein R^(b19), R^(b20) and R^(b21) are independently in eachoccurrence a halogen atom (preferably a fluorine atom), a hydroxylgroup, a C1-C18 aliphatic hydrocarbon group or a C1-C12 alkoxy group,and one or more hydrogen atoms of the aliphatic hydrocarbon group can bereplaced by a hydroxyl group, a C1-C12 alkoxy group or a C6-C18 aromatichydrocarbon group, and one or more hydrogen atoms of the saturatedcyclic hydrocarbon group can be replaced by a halogen atom, aglycidyloxy group or a C2-C4 acyl group, and v2, w2 and x2 independentlyeach represent an integer of 0 to 5.

The aliphatic hydrocarbon group has preferably 1 to 12 carbon atoms, anda C1-C12 alkyl group and a C4-C18 alicyclic hydrocarbon group arepreferable, and v2, w2 and x2 independently each preferably represent 0or 1.

It is preferred that R^(b19), R^(b20) and R^(b21) are independently ineach occurrence a halogen atom, a hydroxyl group, a C1-C12 alkyl groupor a C1-C12 alkoxy group, and v2, w2 and x2 independently each representan integer of 0 to 5. It is more preferred that R^(b19), R^(b20) andR^(b21) are independently in each occurrence a fluorine atom, a hydroxylgroup, a C1-C12 alkyl group or a C1-C12 alkoxy group, and v2, w2 and x2independently each represent 0 or 1.

Examples of the cation represented by the formula (b2-1) include thefollowing.

Examples of the cation represented by the formula (b2-3) include thefollowings.

Examples of the salt represented by the formula (B1) include a saltwherein the anion is any one of the above-mentioned anions and thecation is any one of organic cations. Preferable examples thereofinclude those described in the following Table 1.

TABLE 1 Salt represented by the formula (B1) Anion Cation B1-1P b1-s-2b2-c-1 B1-2P b1-s-2 b2-c-21 B1-3P b1-s-11 b2-c-1 B1-4P b1-s-11 b2-c-2B1-5P b1-s-11 b2-c-6 B1-6P b1-s-11 b2-c-10 B1-7P b1-s-11 b2-c-12 B1-8Pb1-s-11 b2-c-15 B1-9P b1-s-11 b2-c-21 B1-10P b1-s-11 b2-c-23 B1-11Pb1-s-14 b2-c-1 B1-12P b1-s-14 b2-c-2 B1-13P b1-s-14 b2-c-6 B1-14Pb1-s-14 b2-c-10 B1-15P b1-s-14 b2-c-12 B1-16P b1-s-14 b2-c-15 B1-17Pb1-s-14 b2-c-21 B1-18P b1-s-14 b2-c-23 B1-19P b1-s-20 b2-c-1 B1-20Pb1-s-20 b2-c-2 B1-21P b1-s-20 b2-c-6 B1-22P b1-s-20 b2-c-10 B1-23Pb1-s-20 b2-c-12 B1-24P b1-s-20 b2-c-15 B1-25P b1-s-20 b2-c-21 B1-26Pb1-s-20 b2-c-23 B1-27P b1-s-4 b2-c-1 B1-28P b1-s-35 b2-c-1 B1-29Pb1-s-36 b2-c-1 B1-30P b1-s-39 b2-c-1 B1-31P b1-s-40 b2-c-1 B1-32Pb1-s-41 b2-c-1 B1-33P b1-s-42 b2-c-1

Preferable examples of the acid generator include salts represented bythe formulae (B1-1) to (B1-17), the salt containing a triphenylsulfoniumcation or a tritolysulfonium cation is more preferable, and the saltsrepresented by the formulae (B1-2), (B1-3), (B1-6), (B1-7), (B1-11),(B1-12), (B1-13) and (B1-14) are especially preferable.

When the acid generator contains the acid generator other than the saltrepresented by the formula (B1), the content of the salt represented bythe formula (B1) is preferably 70% by mass or more and more preferably90% by mass or more based on the total amount of the acid generator. Theacid generator preferably consists of the salt represented by theformula (31).

The content of the acid generator is usually 1 part by mass or more per100 parts by mass of RESIN (A), and preferably 3 parts by mass or more.The content of the acid generator is usually 40 parts by mass or lessper 100 parts by mass of RESIN (A), and preferably 30 parts by mass orless.

The photoresist compositions of the present invention can contain abasic compound as a quencher. The basic compound has the property thatit can trap an acid, especially an acid generated from the acidgenerator by applying a radiation.

The basic compound is preferably a basic nitrogen-containing organiccompound, and examples thereof include an amine compound such as analiphatic amine and an aromatic amine and an ammonium salt. Examples ofthe aliphatic amine include a primary amine, a secondary amine and atertiary amine. Examples of the aromatic amine include an aromatic aminein which aromatic ring has one or more amino groups such as aniline anda heteroaromatic amine such as pyridine. Preferable examples thereofinclude an aromatic amine represented by the formula (C2):

wherein Ar^(c1) represents an aromatic hydrocarbon group, and R^(c5) andR^(c6) independently represent a hydrogen atom, an aliphatic hydrocarbongroup, a saturated cyclic hydrocarbon group or an aromatic hydrocarbongroup, and the aliphatic hydrocarbon group, the saturated cyclichydrocarbon group and the aromatic hydrocarbon group can have one ormore substituents selected from the group consisting of a hydroxylgroup, an amino group, an amino group having one or two C1-C4 alkylgroups and a C1-C6 alkoxy group.

The aliphatic hydrocarbon group is preferably an alkyl group and thesaturated cyclic hydrocarbon group is preferably a cycloalkyl group. Thealiphatic hydrocarbon group preferably has 1 to 6 carbon atoms. Thesaturated cyclic hydrocarbon group preferably has 5 to 10 carbon atoms.The aromatic hydrocarbon group, preferably has 6 to 10 carbon atoms.

As the aromatic amine represented by the formula (C2), an aminerepresented by the formula (C2-1):

wherein R^(c5) and R^(c6) are the same as defined above, and R^(c7) isindependently in each occurrence an aliphatic hydrocarbon group, analkoxy group, a saturated cyclic hydrocarbon group or an aromatichydrocarbon group, and the aliphatic hydrocarbon group, the alkoxygroup, the saturated cyclic hydrocarbon group and the aromatichydrocarbon group can have one or more substituents selected from thegroup consisting of a hydroxyl group, an amino group, an amino grouphaving one or two C1-C4 alkyl groups and a C1-C6 alkoxy group, and m3represents an integer of 0 to 3, is preferable. The aliphatichydrocarbon group is preferably an alkyl group and the saturated cyclichydrocarbon group is preferably a cycloalkyl group. The aliphatichydrocarbon group preferably has 1 to 6 carbon atoms. The saturatedcyclic hydrocarbon group preferably has 5 to 10 carbon atoms. Thearomatic hydrocarbon group preferably has 6 to 10 carbon atoms. Thealkoxy group preferably has 1 to 6 carbon atoms.

Examples of the aromatic amine represented by the formula (C2) include1-naphthylamine, 2-naphthylamine, aniline, diisopropylaniline,2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, and diphenylamine, and among them,preferred is diisopropylaniline and more preferred is2,6-diisopropylaniline.

Other examples of the basic compound include amines represented by theformulae (C3) to (C11):

wherein R^(c6), R^(c20), R^(c21), and R^(c23) to R^(c28) independentlyrepresent an aliphatic hydrocarbon group, an alkoxy group, a saturatedcyclic hydrocarbon group or an aromatic hydrocarbon group, and thealiphatic hydrocarbon group, the alkoxy group, the saturated cyclichydrocarbon group and the aromatic hydrocarbon group can have one ormore substituents selected from the group consisting of a hydroxylgroup, an amino group, an amino group having one or two C1-C4 alkylgroups and a C1-C6 alkoxy group,R^(c9), R^(c10), R^(c11) to R^(c14), R^(c16) to R^(c19), and R^(c22)independently represents a hydrogen atom, an aliphatic hydrocarbongroup, a saturated cyclic hydrocarbon group or an aromatic hydrocarbongroup, and the aliphatic hydrocarbon group, the saturated cyclichydrocarbon group and the aromatic hydrocarbon group can have one ormore substituents selected from the group consisting of a hydroxylgroup, an amino group, an amino group having one or two C1-C4 alkylgroups and a C1-C6 alkoxy group,R^(c15) is independently in each occurrence an aliphatic hydrocarbongroup, a saturated cyclic hydrocarbon group or an alkanoyl group, L^(c1)and L^(c2) independently represents a divalent aliphatic hydrocarbongroup, —CO—, —C(═NH)—, —C(═NR^(c3))—, —S—, —S—S— or a combinationthereof and represents a C1-C4 alkyl group,O3 to u3 each independently represents an integer of 0 to 3 and n3represents an integer of 0 to 8.

The aliphatic hydrocarbon group has preferably 1 to 6 carbon atoms, andthe saturated cyclic hydrocarbon group has preferably 3 to 6 carbonatoms, and the alkanoyl group has preferably 2 to 6 carbon atoms, andthe divalent aliphatic hydrocarbon group has preferably 1 to 6 carbonatoms. The divalent aliphatic hydrocarbon group is preferably analkylene group.

Examples of the amine represented by the formula (C3) includehexylamine, heptylamine, octylamine, nonylamine, decylamine,dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine,dinonylamine, didecylamine, triethylamine, trimethylamine,tripropylamine, tributylamine, tripentylamine, trihexylamine,triheptylamine, trioctylamine, trinonylamine, tridecylamine,methyldibutylamine, methyldipentylamine, methyldihexylamine,methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine,methyldinonylamine, methyldidecylamine, ethyldibutylamine,ethydipentylamine, ethyldihexylamine, ethydiheptylamine,ethyldioctylamine, ethyldinonylamine, ethyldidecylamine,dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine,triisopropanolamine, ethylenediamine, tetramethylenediamine,hexamethylenediamine, 4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane and4,4′-diamino-3,3′-diethyldiphenylmethane.

Examples of the amine represented by the formula (C4) includepiperazine. Examples of the amine represented by the formula (C5)include morpholine Examples of the amine represented by the formula (C6)include piperidine and hindered amine compounds having a piperidineskeleton as disclosed in JP 11-52575 A. Examples of the aminerepresented by the formula (C7) include 2,2′-methylenebisaniline.Examples of the amine represented by the formula (C8) include imidazoleand 4-methylimidazole. Examples of the amine represented by the formula(C9) include pyridine and 4-methylpyridine. Examples of the aminerepresented by the formula (C10) include di-2-pyridyl ketone,1,2-di(2-pyridyl)ethane, 2,2-di(4-pyridyl)ethane,1,3-di(4-pyridyl)propane, 1,2-bis(2-pyridyl)ethene,1,2-bis(4-pyridyl)ethene, 1,2-di(4-pyridyloxy)ethane, 4,4′-dipyridylsulfide, 4,4′-dipyridyl disulfide, 2,2′-dipyridylamine and2,2′-dipicolylamine. Examples of the amine represented by the formula(C11) include bipyridine.

Examples of the quaternary ammonium hydroxide includetetramethylammonium hydroxide, tetrabutylammonium hydroxide,tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,phenyltrimethylammonium hydroxide,(3-trifluoromethylphenyl)trimethylammonium hydroxide and(2-hydroxyethyl)trimethylammonium hydroxide (so-called “choline”).

when the photoresist compositions contain the basic compound, thecontent thereof is usually 0.01 to 1% by mass based on sum of solidcomponent.

The photoresist compositions of the present invention usually containone or more solvents. Examples of the solvent include a glycol etherester such as ethyl cellosolve acetate, methyl cellosolve acetate andpropylene glycol monomethyl ether acetate; a glycol ether such aspropylene glycol monomethyl ether; an acyclic ester such as ethyllactate, butyl acetate, amyl acetate and ethyl pyruvate; a ketone suchas acetone, methyl isobutyl ketone, 2-heptanone and cyclohexanone; and acyclic ester such as γ-butyrolactone.

The amount of the solvent is usually 90% by mass or more, preferably 92%by mass or more preferably 94% by mass or more based on total amount ofthe photoresist composition of the present invention. The amount of thesolvent is usually 99.9% by mass or less and preferably 99% by mass orless based on total amount of the photoresist composition of the presentinvention.

The photoresist compositions of the present invention can contain, ifnecessary, a small amount of various additives such as a sensitizer, adissolution inhibitor, other polymers, a surfactant, a stabilizer and adye as long as the effect of the present invention is not prevented.

The photoresist compositions of the present invention are useful for achemically amplified photoresist composition.

A photoresist pattern can be produced by the following steps (1) to (5):

(1) a step of applying the first or second photoresist composition ofthe present invention on a substrate,

(2) a step of forming a photoresist film by conducting drying,

(3) a step of exposing the photoresist film to radiation,

(4) a step of baking the exposed photoresist film, and

(5) a step of developing the baked photoresist film with an alkalinedeveloper, thereby forming a photoresist pattern.

The applying of the photoresist composition on a substrate is usuallyconducted using a conventional apparatus such as spin coater. Thephotoresist composition is preferably filtrated with filter having apore size of 0.01 to 0.2 μm before applying. Examples of the substrateinclude a silicon wafer or a quartz wafer on which a sensor, a circuit,a transistor or the like is formed.

The formation of the photoresist film is usually conducted using aheating apparatus such as hot plate or a decompressor, and the heatingtemperature is usually 50 to 200° C., and the operation pressure isusually 1 to 1.0*10⁵ Pa.

The photoresist film obtained is exposed to radiation using an exposuresystem. The exposure is usually conducted through a mask having apattern corresponding to the desired photoresist pattern. Examples ofthe exposure source include a light source radiating laser light in aUV-region such as a KrF excimer laser (wavelength: 248 nm), an ArFexcimer laser (wavelength: 193 nm) and a F₂ laser (wavelength: 157 nm),and a light source radiating harmonic laser light in a far UV region ora vacuum UV region by wavelength conversion of laser light from a solidlaser light source (such as YAG or semiconductor laser).

The temperature of baking of the exposed photoresist film is usually 50to 200° C., and preferably 70 to 150° C.

The development of the baked photoresist film is usually carried outusing a development apparatus. The alkaline developer used may be anyone of various alkaline aqueous solution used in the art. Generally, anaqueous solution of tetramethylammonium hydroxide or(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as“choline”) is often used. After development, the photoresist patternformed is preferably washed with ultrapure water, and the remained wateron the photoresist pattern and the substrate is preferably removed.

The photoresist composition of the present invention provides aphotoresist pattern showing good Exposure Latitude (EL), and therefore,the photoresist composition of the present invention is suitable for ArFexcimer laser lithography, KrF excimer laser lithography, ArF immersionlithography, EUV (extreme ultraviolet) lithography, EUV immersionlithography and EB (electron beam) lithography. Further, the photoresistcomposition of the present invention can especially be used for EUVlithography and EB lithography.

EXAMPLES

The present invention will be described more specifically by Examples,which are not construed to limit the scope of the present invention.

The “%” and “part(s)” used to represent the content of any component andthe amount of any material used in the following examples andcomparative examples are on amass basis unless otherwise specificallynoted. The weight-average molecular weight of any material used in thefollowing examples is a value found by gel permeation chromatography[Column: Three of =gel Multipore HXL-M with guard column, manufacturedby TOSOH CORPORATION, Solvent; tetrahydrofuran, Flow rate: 1.0 mL/min.,Detector: RI Detector, Column temperature: 40° C., Injection volume; 100μL] using standard polystyrene as a standard reference material. Theratio of the structural units in the resin was decided by measuring theamounts of the unreacted monomers in the reaction after polymerizationfollowed by calculating the amount of the reacted monomers from theresult measured.

Example 1

Into a reactor, added were 14.00 parts of the compound represented bythe formula (I-1) (commodity name: NSTABu, manufactured by IDEMITSU) and140 parts of chloroform. The resultant mixture was stirred at 23° C. for30 minutes, and then, 52.45 parts of the compound represented by theformula (I-2) was added dropwise thereto. The resultant mixture wasstirred at 23° C. for 1 hour and then, 52.45 parts of the compoundrepresented by the formula (I-2) was added dropwise thereto. Theresultant mixture was stirred at 23° C. for 2 hours and then, 52.45parts of the compound represented by the formula (I-2) was addeddropwise thereto. The resultant mixture was stirred at 23° C. for 1hour. The reaction mixture obtained was concentrated. To the residueobtained, 20 parts of chloroform was added followed by conductingstirring and concentrating. To the residue obtained, 30 parts of heptanewas added. The resultant mixture was stirred for 30 minutes, and then,filtrated to obtain 11.19 parts of the compound represented by theformula (I-3).

Into a reactor, added were 10.03 parts of the compound represented bythe formula (I-3) and 60.18 parts of acetonitrile. The resultant mixturewas stirred at 23° C. for 30 minutes, and then, 6.92 parts of thecompound represented by the formula (I-4) was added thereto. Theresultant mixture was stirred at 23° C. for 1.5 hours and then, 4.33parts of the compound represented by the formula (I-5) and 2.17 parts ofacetonirile were added thereto. The resultant mixture was stirred at 23°C. for 8 hours. After removing insoluble matter by filtration, to thefiltrate obtained, 76.86 parts of 5% aqueous oxalic acid solution and187.04 parts of ethyl acetate were added. The resultant mixture wasstirred for 30 minutes followed by separation. The organic layerobtained was washed with 93.52 parts of ion-exchanged water. Thiswashing was repeated five times . The organic layer was concentrated toobtain 10.45 parts of the compound represented by the formula (M-I).

MS: 360.1 (molecular ion peak)

Example 2

Into a reactor, added were 10.03 parts of the compound represented bythe formula (I-3) and 60.18 parts of acetonitrile. The resultant mixturewas stirred at 23° C. for 30 minutes, and then, 6.92 parts of thecompound represented by the formula (I-4) was added thereto. Theresultant mixture was stirred at 23° C. for 1.5 hours and then, 4.30parts of the compound represented by the formula (J-5) and 2.15 parts ofacetonirile were added thereto. The resultant mixture was stirred at 23°C. for 8 hours. After removing insoluble matter by filtration, to thefiltrate obtained, 76.86 parts of 5% aqueous oxalic acid solution and187.04 parts of ethyl acetate were added. The resultant mixture wasstirred for 30 minutes followed by separation. The organic layerobtained was washed with 93.52 parts of ion-exchanged water. Thiswashing was repeated five times. The organic layer was concentrated toobtain 10.22 parts of the compound represented by the formula (M-J).

MS: 359.1 (molecular ion peak)

Example 3

To 3.64 parts of tetrahydrofuran, 0.26 part of lithium hydride was addedat 0° C. To the mixture obtained, a solution prepared by mixing 1.78parts of the compound represented by the formula (1-3) with 9.10 partsof tetrahydrofuran was added over 20 minutes. The resultant mixture washeated up to 23° C., and then, stirred at the same temperature for 2hours. The reaction mixture was added dropwise to 20 parts of 6Nhydrochloric acid, and then, 30 parts of tert-butyl methyl ether and 30parts of ion-exchanged water were added to the mixture obtained. Theresultant mixture was separated to an organic layer and an aqueouslayer. The organic layer was washed with 30 parts of ion-exchangedwater. This washing was repeated five times. The organic layer wasconcentrated. To the residue obtained, 10 parts of ethyl acetate wasadded, and the resultant mixture was stirred for 30 minutes followed byfiltrating to obtain 0.89 part of the compound represented by theformula (L-1).

To the mixture obtained by mixing 0.72 part of the compound representedby the formula (L-1), 0.92 part of N-methylpyrrolidine and 20 parts ofmethyl isobutyl ketone, 0.64 part of the compound represented by theformula (L-2) was added. The resultant mixture was stirred at 60° C. for24 hours. To the reaction mixture obtained, 10 parts of ion-exchangedwater and 20 parts of methyl isobutyl ketone were added followed byconducting separation. The organic layer obtained was washed with water.This washing was repeated three times. The organic layer wasconcentrated, and the residue was purified with column chromatography(silica gel 60-200 mesh, manufactured by Merck, solvent: ethyl acetate)to obtain 0.31 part of the compound represented by the formula (M-L).

MS: 302.1 (molecular ion peak)

Example 4

Into a reactor, 33.25 parts of the compound represented by the formula(M-1), 23.93 parts of dicyclohexylcarbodiimide and 40.00 parts ofdichloromethane were added. The resultant mixture was cooled to about 0°C., and then, 18.83 parts of the compound represented by the formula(M-2) was added thereto. The resultant mixture was stirred at about 0°C. for 1 hour followed by stirring at 23° C. for 30 minutes . Afterremoving insoluble matter by filtration, the filtrated obtained wasconcentrated to obtain 44.19 parts of the compound represented by theformula (M-3).

Into a reactor, 19.33 parts of the compound represented by the formula(M-3), 19.02 parts of the compound represented by the formula (M-4) and200 parts of acetonitrile were added. The resultant mixture was stirredat 50° C. for 3 hours. The reaction mixture obtained was concentrated.To the residue obtained, 300 parts of chloroform and 150 parts ofion-exchanged water were added followed by conducting separation. Theorganic layer obtained was washed with 150 parts of ion-exchanged water.The organic layer was concentrated, and the residue was purified withcolumn chromatography (silica gel 60-200 mesh, manufactured by Merck,solvent: ethyl acetate) to obtain 14.58 parts of the compoundrepresented by the formula (M-M).

MS: 315.1 (molecular ion peak)

Monomers used in the following Examples are following monomers (M-A),(M-B), (M-c), (M-D), (M-E), (M-F), (M-G), (M-H), (M-I), (M-J), (M-K),(M-L), (M-M) and (M-N).

Example 5

The monomers (M-A), (M-E), (M-B), (M-C) and (M-I) were mixed in a molarratio of 32/7/8/43/10 (monomer (M-A)/monomer (M-E)/monomer (M-B)/monomer(M-C)/monomer (M-I)), and 1,4-dioxane in 1.5 times part based on totalparts of all monomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimethylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation. This operation wasrepeated twice for purification. As a result, a resin having aweight-average molecular weight of about 9.5×10³ was obtained in a yieldof 85%. This resin is called as resin A1. Resin A1 had the followingstructural units, and the molar ratio of the structural units((u-A)/(u-E)/(u-B)/(u-C)/(u-I)) was 27.6/5.7/8.7/47.1/10.9.

Example 6

The monomers (M-F), (M-E), (M-B), (M-C) and (M-I) were mixed in a molarratio of 35/10/6/37/12 (monomer (M-F)/monomer (M-E)/monomer(M-B)/monomer (M-C)/monomer (M-I)), and 1,4-dioxane in 1.5 times partbased on total parts of all monomers was added to prepare a solution. Tothe solution, azobisisobutyronitrile as an initiator in a ratio of 1 mol% based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 73° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation. The precipitate was collected by filtration andthen, was dissolved in 1,4-dioxane followed by poured the resultantsolution into a large amount of a mixture of methanol and water to causeprecipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 8.0×10³ was obtainedin a yield of 79%. This resin is called as resin A2. Resin A2 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-E)/(u-B)/(u-C)/(u-I)) was 27.9/9.8/6.7/42.2/13.5.

Example 7

The monomers (M-A), (M-E), (M-B), (M-D), (M-C) and (M-I) were mixed in amolar ratio of 32/7/8/10/33/10 (monomer (M-A)/monomer (M-E)/monomer(M-B)/monomer (M-D)/monomer (M-C)/monomer (M-I)), and 1,4-dioxane in 1.5times part based on total parts of all monomers was added to prepare asolution. To the solution, azobisisobutyronitrile as an initiator in aratio of 1 mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 73° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.9×10³ was obtainedin a yield of 74%. This resin is called as resin A3. Resin A3 had thefollowing structural units, and the molar ratio of the structural units((u-A)/(u-E)/(u-B)/(u-D)/(u-C)/(u-I)) was 27.5/6.8/8.7/11.2/35.0/10.8.

Example 8

The monomers (M-F), (M-E), (M-C) and (M-J) were mixed in a molar ratioof 35/10/6/37/12 (monomer (M-F)/monomer (M-E)/monomer (M-B)/monomer(M-C)/monomer (M-J)), and 1,4-dioxane in 1.5 times part based on totalparts of all monomers was added to prepare a solution. To the solution,azobisisobutyronitrile as an initiator in a ratio of 1 mol % based onall monomer molar amount and azobis(2,4-dimothylvaleronitrile) as aninitiator in a ratio of 3 mol % based on all monomer molar amount wereadded, and the obtained mixture was heated at 73° C. for about 5 hours.The reaction mixture obtained was poured into a large amount of amixture of methanol and water to cause precipitation. The precipitatewas collected by filtration and then, was dissolved in 1,4-dioxanefollowed by poured the resultant solution into a large amount of amixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 8.0×10³ was obtainedin a yield of 79%. This resin is called as resin A4. Resin A4 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-M)/(u-B)/(u-C)/(u-J)) was 27.8/9.9/6.8/42.4/13.2.

Example 9

The monomers (M-F), (M-K), (M-B), (M-C) and (M-I) were mixed in a molarratio of 35/10/6/37/12 (monomer (M-F)/monomer (M-K)/monomer(M-B)/monomer (M-C)/monomer (M-I)), and 1,4-dioxane in 1.5 times partbased on total parts of all monomers was added to prepare a solution. Tothe solution, azobisisobutyronitrile as an initiator in a ratio of 1 mol% based an all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 73° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation. The precipitate was collected by filtration andthen, was dissolved in 1,4-dioxane followed by poured the resultantsolution into a large amount of a mixture of methanol and water to causeprecipitation. This operation was repeated twice for purification. As aresult, a resin having a weight-average molecular weight of about7.6×10³ was obtained in a yield of 64%. This resin is called as resinA6. Resin A6 had the following structural units, and the molar ratio ofthe structural units ((u-F)/(u-K)/(u-B)/(u-C)/(u-I)) was27.9/10.1/6.6/42.1/13.3.

Example 10

The monomers (M-F), (M-E), (M-B), (M-D), (M-C) and (M-I) were mixed in amolar ratio of 30/14/6/10/30/10 (monomer (M-F)/monomer (M-E)/monomer(M-B)/monomer (M-D)/monomer (M-C)/monomer (M-I)) and 1,4-dioxane in 1.5times part based on total parts of all monomers was added to prepare asolution. To the solution, azobisisobutyronitrile as an initiator in aratio of 1 mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 73° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.8×10³ was obtainedin a yield of 67%. This resin is called as resin A7. Resin A7 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-E)/(u-B)/(u-D)/(u-C)/(u-I)) was 21.1/14.5/6.5/11.4/35.4/11.1.

Example 11

The monomers (M-F), (M-K), (M-B), (M-D), (M-C) and (M-I) were mixed in amolar ratio of 30/14/6/10/30/10 (monomer (M-F)/monomer (M-K)/monomer(M-B)/monomer (M-D)/monomer (M-C)/monomer (M-I)) and 1,4-dioxane in 1.5times part based on total parts of all monomers was added to prepare asolution. To the solution, azobisisobutyronitrile as an initiator in aratio of 1 mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 73° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.4×10³ was obtainedin a yield of 66%. This resin is called as resin A8. Resin A8 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-K)/(u-B)/(u-D) (u-C)/(u-I)) was 21.2/14.4/6.6/11.4/35.3/11.1.

Example 12

The monomers (M-F), (M-K), (M-B), (M-D), (M-C) and (M-L) were mixed in amolar ratio of 30/14/6/10/30/10 (monomer (M-F)/monomer (M-K)/monomer(M-B)/monomer (M-D)/monomer (M-C)/monomer (M-L)), and 1,4-dioxane in 1.5times part based on total parts of all monomers was added to prepare asolution. To the solution, azobisisobutyronitrile as an initiator in aratio of 1 mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 73° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.8×10³ was obtainedin a yield of 63%. This resin is called as resin A9. Resin A9 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-K)/(u-B)/(u-D)/(u-C)/(u-L)) was 21.2/14.5/6.7/11.5/35.5/10.6.

Example 13

The monomers (M-F), (M-E), (M-B), (M-C) and (M-M) were mixed in a molarratio of 35/10/6/37/12 (monomer (M-F)/monomer (M-E)/monomer(M-B)/monomer (M-C)/monomer (M-M)), and 1,4-dioxane in 1.5 times partbased on total parts of all monomers was added to prepare a solution. Tothe solution, azobisisobutyronitrile as an initiator in a ratio of 1mold based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 75° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation. The precipitate was collected by filtration andthen, was dissolved in 1,4-dioxane followed by poured the resultantsolution into a large amount of a mixture of methanol and water to causeprecipitation. This operation was repeated twice for purification. As aresult, a resin having a weight-average molecular weight of about7.2×10³ was obtained in a yield of 65%. This resin is called as resinA10.

Resin A10 had the following structural units, and the molar ratio of thestructural units ((u-F)/(u-E)/(u-E)/(u-c)/(u-M)) was23.8/11.2/7.6/43.9/13.5.

Example 14

The monomers (M-F), (M-E), (M-B), (M-D), (M-C) and (M-M) were mixed in amolar ratio of 35/10/8/12/23/12 (monomer (M-F)/monomer (M-E)/monomer(M-B)/monomer (M-D)/monomer (M-C)/monomer (M-M)), and 1,4-dioxane in 1.5times part based on total parts of all monomers was added to prepare asolution. To the solution, azobisisobutyronitrile as an initiator in aratio of 1 molds based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 75° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation .

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.4×10³ was obtainedin a yield of 66%. This resin is called as resin A11. Resin A11 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-E)/(u-B)/(u-D)/(u-C)/(u-M)) was 23.8/11.6/9.2/14.3/27.3/13.8.

Example 15

The monomers (M-F), (M-K), (M-B), (M-D) (M-C) and (M-M) were mixed in amolar ratio of 30/14/6/10/30/10 (monomer (M-F)/monomer (M-K)/monomer(M-B)/monomer (M-D)/monomer (M-C)/monomer (M-M)), and 1,4-dioxane in 1.5times part based on total parts of all monomers was added to prepare asolution. To the solution, azobisisobutyronitrile as an initiator in aratio of 1 mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 75° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.6×10³ was obtainedin a yield of 65%. This resin is called as resin A12. Resin A12 had thefollowing structural units, and the molar ratio of the structural units((u-F)/(u-K)/(u-B)/(u-D)/(u-C)/(u-M) was 21.2/14.0/6.5/12.8/35.3/10.2.

Resin Synthesis Example 1

The monomers (M-A), (M-H) and (M-G) were mixed in a molar ratio of52.6/15.8/31.6 (monomer (M-A)/monomer (M-H)/monomer (M-G)), and1,4-dioxane in 1.5 times part based on total parts of all monomers wasadded to prepare a solution. To the solution, azobisisobutyronitrile asan initiator in a ratio of 1 mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 78° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation.

The precipitate was collected by filtration and then, was dissolved in1,4-dioxane followed by poured the resultant solution into a largeamount of a mixture of methanol and water to cause precipitation.

This operation was repeated twice for purification. As a result, a resinhaving a weight-average molecular weight of about 7.3×10³ was obtainedin a yield of 68%. This resin is called as resin A5. Resin A5 had thefollowing structural units, and the molar ratio of the structural units((u-A)/(u-H)/(u-G)) was 43.0/16.1/40.9.

Resin Synthesis Example 2

The monomers (M-F) (M-B), (M-C) and (M-N) were mixed in a molar ratio of51.7/7.8/23.3/17.2 (monomer (M-F)/monomer (M-B)/monomer (M-C)/monomer(M-N)), and 1,4-dioxane in 1.5 times part based on total parts of allmonomers was added to prepare a solution.

To the solution, azobisisobutyronitrile as an initiator in a ratio of 1mol % based on all monomer molar amount andazobis(2,4-dimethylvaleronitrile) as an initiator in a ratio of 3 mol %based on all monomer molar amount were added, and the obtained mixturewas heated at 75° C. for about 5 hours. The reaction mixture obtainedwas poured into a large amount of a mixture of methanol and water tocause precipitation. The precipitate was collected by filtration andthen, was dissolved in 1,4-dioxane followed by poured the resultantsolution into a large amount of a mixture of methanol and water to causeprecipitation. This operation was repeated twice for purification. As aresult, a resin having a weight-average molecular weight of about7.7×10³ was obtained in a yield of 64%. This resin is called as resinA13. Resin A13 had the following structural units, and the molar ratioof the structural units ((u-F)/(u-B)/(u-C)/(u-N)) was33.3/10.4/32.2/24.1.

Examples 16 to 28 and Comparative Examples 1 to 2 <Resin> Resin A1, A2,A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13 <Acid Generator>

<Quencher>

C1: 2,6-diisopropylaniline

<Solvent>

E1: propylene glycol monomethyl ether acetate 263 parts propylene glycolmonomethyl ether  20 parts 2-heptanone  20 parts γ-butyrolactone  3.5parts

The following components were mixed and dissolved, further, filtratedthrough a fluorine resin filter having pore diameter of 0.2 μm, toprepare photoresist compositions.

Resin (kind and amount are described in Table 2)

Acid generator (kind and amount are described in Table 2)

Quencher (kind and amount are described in Table 2)

Solvent E1

TABLE 2 Resin Acid generator Quencher Ex. (kind/amount (kind/amount(kind/amount PB PEB No. (part)) (part)) (part)) (° C.) (° C.) Ex. 16 A1/10 B1/1.10 C1/0.07 105 100 Ex. 17  A2/10 B1/1.10 C1/0.07 90 85 Ex.18  A3/10 B1/1.10 C1/0.07 105 100 Ex. 19  A4/10 B2/1.10 C1/0.07 90 85Ex. 20  A1/10 B1/1.10 C1/0.07 90 85 Ex. 21  A6/10 B1/1.10 C1/0.07 90 85Ex. 22  A7/10 B1/1.10 C1/0.07 90 85 Ex. 23  A8/10 B1/1.10 C1/0.07 90 85Ex. 24  A9/10 B1/1.10 C1/0.07 90 85 Ex. 25 A10/10 B1/1.10 C1/0.07 90 85Ex. 26 A11/10 B1/1.10 C1/0.07 90 85 Ex. 27 A11/10 B3/1.10 C1/0.07 90 85Ex. 28 A12/10 B1/1.10 C1/0.07 90 85 Comp.  A5/10 B2/1.10 C1/0.07 105 100Ex. 1 Comp. A13/10 B3/1.10 C1/0.07 90 85 Ex. 2

Silicon wafers (12 inches) were each coated with “ARC-29”, which is anorganic anti-reflective coating composition available from NissanChemical Industries, Ltd., and then baked at 205° C. for 60 seconds, toform a 780 Å-thick organic anti-reflective coating.

Each of the photoresist compositions prepared as above was spin-coatedover the anti-reflective coating so that the thickness of the resultingfilm became 85 nm after drying. The silicon wafers thus coated with therespective photoresist compositions were each prebaked on a directhotplate at a temperature shown in the column “PB” in Table 2 for 60seconds. Using an ArF excimer stepper for immersion exposure (“XT:1900Gi” manufactured by ASML, NA=1.35, 3/4 Annular, X—Y polarization),each wafer thus formed with the respective resist film was subjected tocontact hole pattern exposure using a photomask for forming a contacthole pattern having a hole pitch of 100 nm and a hole diameter of 70 nmwith the exposure quantity being varied stepwise. Ultrapure water wasused as an immersion medium.

After the exposure, each wafer was subjected to post-exposure baking ona hotplate at a temperature shown in the column “PEB” in Table 2 for 60seconds and then to paddle development for 60 seconds with an aqueoussolution of 2.38% by mass tetramethylammonium hydroxide.

Each of patterns developed on the organic anti-reflective coatingsubstrate after the development was observed with a scanning electronmicroscope, the results of which are shown in Table 3 and Table 4.

Effective sensitivity (ES): It was expressed as the amount of exposurethat the hole diameter of the contact hole pattern became 55 nm afterexposure and development.

CD uniformity (CDU): The photoresist pattern at ES was observed with ascanning electronmicroscope. The hole diameter of the contact holepattern was twenty four times measured and its average diameter wascalculated. The average diameters of four hundred holes on the samewafer were respectively measured. When population was the averagediameters of four hundred holes, the standard deviation (CDU) wascalculated. The smaller the standard deviation is, the better patternprofile is.

Focus margin (DOF): The photoresist patterns were obtained at ES withthe focal point distance being varied stepwise. Each of patternsdeveloped on the organic anti-reflective coating substrate after thedevelopment were observed and the focal point distances when thepatterns of which hole diameter was 52.2 nm or more and 57.7 nm or lesswere obtained were measured and the difference between the max value ofthe focal point distance and the minimum value of the focal pointdistance (DOF) was calculated.

The bigger difference is, the better focus margin (DOF) of thephotoresist pattern is.

TABLE 3 Ex. No. CDU Ex. 16 1.86 Ex. 17 1.74 Ex. 18 1.81 Ex. 19 1.78 Ex.20 1.98 Ex. 21 1.72 Ex. 22 1.71 Ex. 23 1.68 Ex. 24 1.70 Comp. Ex. 1 2.45

TABLE 4 Ex. No. DOF Ex. 25 0.20 Ex. 26 0.22 Ex. 27 0.18 Ex. 28 0.22Comp. Ex. 2 0.17

The photoresist composition comprising the resin of the presentinvention provides a photoresist pattern having a good CD uniformity andfocus margin.

1. A resin comprising a structural unit represented by the formula (aa):

wherein T¹ represents a C4-C34 sultone ring group optionally having oneor more substituents, X² represents —O— or —N(R^(c))—, R^(c) representsa hydrogen atom or a C1-C6 alkyl group, when X² is —O—, Z¹ represents*—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹—, when X² is —N(R^(c))—, Z¹ represents *—X¹—,*—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³—, *—X¹—CO—X⁴—X³—, *—X¹—X⁴—CO—X³—CO—or *—X¹—CO—X⁴—X³—CO—, X¹ and X³ independently each represent a C1-C6divalent aliphatic hydrocarbon group, X⁴ represents —O— or —N(R^(c))—, *represents a binding position to X², and R¹ represents a C1-C6 alkylgroup optionally having one or more halogen atoms, a hydrogen atom or ahalogen atom.
 2. The resin according to claim 1, wherein X² is —O— or—N(R^(c))— and Z¹ is *—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X³—N(R^(c))—CO—X¹— in the formula (aa).
 3. The resin according toclaim 1, wherein X² is —NH—, and Z¹ represents *—X¹—, *—X¹—O—X³—,*—X¹—CO—, *—X¹—X⁴—CO—X³—, *—X¹—CO—X⁴—X³—, *—X¹—X⁴—CO—X³—CO— or*—X¹—CO—X⁴—X³—CO— in the formula (aa).
 4. The resin according to claim1, wherein the C1-C6 divalent aliphatic hydrocarbon group is a C1-C6alkanediyl group.
 5. The resin according to any one of claims 1 to 4,wherein T¹ is a polycyclic sultana ring group in the formula (aa). 6.The resin according to any one of claims 1 to 4, wherein T¹ is a grouprepresented by the formula (T1):

wherein X¹¹, X¹² and X¹³ independently each represent —O—, —S— or —CH₂—,one or two hydrogen atoms in —CH₂— in the formula (T1) may be replacedby a halogen atom, a hydroxyl group, a cyano group, a C1-C12 alkyl groupoptionally having a halogen atom or a hydroxyl group, a C1-C12 alkoxygroup, a C6-C12 aryl group, a C7-C12 aralkyl group, a glycidyloxy group,a C2-C12 alkoxycarbonyl group or a C2-C4 acyl group, and * represents abinding position to —O—, in the formula (aa).
 7. The resin according toclaim 1, wherein —X²—Z¹— is —O—CH₂—CH₂—, —O—CH₂—CH₂—O—CO—CH₂— or—O—CH₂—CH₂—NH—CO—CH₂— in the formula (aa).
 8. The resin according toclaim 1, wherein —X²—Z¹— is —NH—CH₂—O— in the formula (aa).
 9. The resinaccording to claim 1, wherein the resin is one being insoluble or poorlysoluble in an aqueous alkali solution but becoming soluble in an aqueousalkali solution by the action of an acid.
 10. A photoresist compositioncomprising the resin according to claim 9 and an acid generator.
 11. Thephotoresist composition according to claim 10, which further comprises asolvent.
 12. The photoresist composition according to claim 10, whichfurther comprises a basic compound.
 13. The photoresist compositionaccording to claim 11, which further comprises a basic compound.
 14. Aprocess for producing a photoresist pattern comprising: (1) a step ofapplying the photoresist composition according to claim 10, claim 11,claim 12 or claim 13 on a substrate to form a photoresist compositionlayer, (2) a step of forming a photoresist film by drying thephotoresist composition layer formed, (3) a step of exposing thephotoresist film to radiation, (4) a step of heating the photoresistfilm after exposing, and (5) a step of developing the photoresist filmafter heating.
 15. A compound represented by the formula (aa′):

wherein T¹ represents a C4-C34 sultone ring group optionally having oneor more substituents, X² represents —O— or —N(R^(c))—, R^(c) representsa hydrogen atom or a C1-C6 alkyl group, when X² is —O—, Z¹ represents*—X¹—, *—X³—CO—O—X¹—, *—X³—CO—N(R^(c))—X¹—, *—X³—O—CO—X¹— or*—X²—N(R^(c))—CO—X¹—, when X² is —N(R^(c))—, Z¹ represents *—X¹—,*—X¹—O—X³—, *—X¹—CO—, *—X¹—X⁴—CO—X³—, *—X¹—CO—X⁴—X³—, *—X¹—X⁴—CO—X³—CO—or *—X¹—CO—X⁴—X³—CO—, X¹ and X³ independently each represent a C1-C6divalent aliphatic hydrocarbon group, X⁴ represents —O— or —N(R^(c))—, *represents a binding position to X², and R¹ represents a C1-C6 alkylgroup optionally having one or more halogen atoms, a hydrogen atom or ahalogen atom.